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Sample records for cihr stirs controversy

  1. Sticking to the knitting: CIHR, innovation and Canadian biotech.

    PubMed

    Edelson, Jeff

    2005-01-01

    The novel proposal outlined by Glenn Brimacombe suggests that the federal government directly participate in funding incremental venture capital investment in Canadian biotechnology, with the goal of facilitating commercialization of Canadian biotechnology and health sciences intellectual property. In this way, they suggest, the economic development benefits of the Canadian current investment in health sciences will be increased. The proposal is based on two premises that need further evaluation: (1) the biotechnology sector in Canada presently underperforms in terms of value creation; (2) this underperformance is due to inadequate venture capital investment. It is the author's view that, although several measures do suggest relative system underperformance, this is likely due to structural differences rather than inadequate venture capital investment. The absence of large, integrated, global biopharmaceutical firms based in Canada, the large number of very small biotech firms and the absence of a clear federal policy mandate supporting technology transfer and underinvestment in public sector funded basic research may all be contributory factors. Given the Canadian biotech sector's current efficiency at creating value from limited public investment in basic science, increasing the core CIHR budget might be an even better investment opportunity for limited incremental funding.

  2. Silencing of molt-regulating transcription factor gene, CiHR3, affects growth and development of sugarcane stem borer, Chilo infuscatellus.

    PubMed

    Zhang, Yu-liang; Zhang, Shu-zhen; Kulye, Mahesh; Wu, Su-ran; Yu, Nai-tong; Wang, Jian-hua; Zeng, Hong-mei; Liu, Zhi-xin

    2012-01-01

    RNA interference (RNAi) is a technology for conducting functional genomic studies and a potential tool for crop protection against insect pests. Development of reliable methods for production and delivery of double-stranded RNA (dsRNA) is the major challenge for efficient pest control. In this study, Chilo infuscatellus Snellen (Crambidae: Lepidoptera) was fed with CiHR3 dsRNA expressed in bacteria or synthesized in vitro. The dsRNA ingested by C. infuscatellus successfully triggered silencing of the molt-regulating transcription factor CiHR3, an important gene for insect growth and development, and caused significant abnormalities and weight loss in insects within seven days of treatment. This study is an ideal example of feeding-based RNAi mediated by dsRNA expressed in bacteria or synthesized in vitro. The results also suggested that feeding-based RNA interference is a potential method for the management of C. infuscatellus.

  3. 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)

  4. 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.

  5. [Cloning - controversies].

    PubMed

    Twardowski, T; Michalska, A

    2001-01-01

    Cloning of the human being is not only highly controversial; in the opinion of the authors it is impossible - we are not able to reproduce human behaviour and character traits. Reproduction through cloning is limited to personal genome resources. The more important is protection of genomic characteristics as private property and taking advantage of cloning for production of the human organs directly or through xenotransplants. In this paper we present the legislation related to cloning in Poland, in the European Union and other countries. We also indicate who and why is interested in cloning.

  6. 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…

  7. 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.

  8. 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)

  9. 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.

  10. Friction-Stir Processing

    DTIC Science & Technology

    2006-01-01

    fatigue results for friction stir welded 2219 aluminum in the following conditions: 1) milled, 2) milled + LPB, 3) milled + 100 hours in a salt...same alloy following friction stir processing. Increased fatigue life in 5083-H321 aluminum fusion welds It will not be possible to friction...fine grain and weld defects near the surface will be eliminated. Potential benefits include both increased corrosion resistance and fatigue life

  11. Friction Stir Welding Development

    NASA Technical Reports Server (NTRS)

    Romine, Peter L.

    1998-01-01

    The research of this summer was a continuation of work started during the previous summer faculty fellowship period. The Friction Stir Welding process (FSW) patented by The Welding Institute (TWI), in Great Britain, has become a popular topic at the Marshall Space Flight Center over the past year. Last year it was considered a novel approach to welding but few people took it very seriously as a near term solution. However, due to continued problems with cracks in the new aluminum-lithium space shuttle external tank (ET), the friction stir process is being mobilized at full speed in an effort to mature this process for the potential manufacture of flight hardware. It is now the goal of NASA and Lockheed-Martin Corporation (LMC) to demonstrate a full-scale friction stir welding system capable of welding ET size barrel sections. The objectives this summer were: (1) Implementation and validation of the rotating dynamometer on the MSFC FSW system; (2) Collection of data for FSW process modeling efforts; (3) Specification development for FSW implementation on the vertical weld tool; (4) Controls and user interface development for the adjustable pin tool; and (5) Development of an instrumentation system for the planishing process. The projects started this summer will lead to a full scale friction stir welding system that is expected to produce a friction stir welded shuttle external tank type barrel section. The success of this could lead to the implementation of the friction stir process for manufacturing future shuttle external tanks.

  12. Planar oscillatory stirring apparatus

    NASA Astrophysics Data System (ADS)

    Wolf, M. F.

    1985-08-01

    The present invention is directed to an apparatus for stirring materials using planar orthogonal axes oscillations. The apparatus has a movable slide plate sandwiched between two fixed parallel support plates. Pressurized air is supplied to the movable slide plate which employs a tri-arm air bearing vent structure which allows the slide plate to float and to translate between the parallel support plates. The container having a material to be stirred is secured to the upper surface of the slide plate through an aperture in the upper support plate. A motor driven eccentric shaft loosely extends into a center hole bearing of the slide plate to cause the horizontal oscillations. Novelty lies in the combination of elements which exploits the discovery that low frequency, orthogonal oscillations applied horizontally to a Bridgman crucible provides a very rigorous stirring action, comparable with and more effective by an order of magnitude than the accelerated crucible rotation technique.

  13. Planar oscillatory stirring apparatus

    NASA Technical Reports Server (NTRS)

    Wolf, M. F. (Inventor)

    1985-01-01

    The present invention is directed to an apparatus for stirring materials using planar orthogonal axes oscillations. The apparatus has a movable slide plate sandwiched between two fixed parallel support plates. Pressurized air is supplied to the movable slide plate which employs a tri-arm air bearing vent structure which allows the slide plate to float and to translate between the parallel support plates. The container having a material to be stirred is secured to the upper surface of the slide plate through an aperture in the upper support plate. A motor driven eccentric shaft loosely extends into a center hole bearing of the slide plate to cause the horizontal oscillations. Novelty lies in the combination of elements which exploits the discovery that low frequency, orthogonal oscillations applied horizontally to a Bridgman crucible provides a very rigorous stirring action, comparable with and more effective by an order of magnitude than the accelerated crucible rotation technique.

  14. Critical Rhetorics of Controversy.

    ERIC Educational Resources Information Center

    Ono, Kent A.; Sloop, John M.

    1999-01-01

    Responds to two articles in the same issue of this journal regarding a controversy over the African Burial Ground in New York City. Raises a third set of questions, arguing that investigations of rhetorics of controversy can also include investigations of the rhetorics of incommensurability, investigating the development of logics and…

  15. STIR: Advanced Quantum Sensing

    DTIC Science & Technology

    2014-07-18

    STIR: Advanced Quantum Sensing Recycling unmeasured photons in a system utilizing weak measurements can substantially improve the signal-to- noise...Quantum Sensing Report Title Recycling unmeasured photons in a system utilizing weak measurements can substantially improve the signal-to-noise ratio. We...Kevin Lyons, Andrew N. Jordan, Trent M. Graham, Paul G. Kwiat. Strengthening weak- value amplification with recycled photons , Physical Review A, (08

  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. Effect of Stirring Method on Protein Crystallization

    NASA Astrophysics Data System (ADS)

    Yaoi, Mari; Adachi, Hiroaki; Takano, Kazufumi; Matsumura, Hiroyoshi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

    2004-10-01

    We previously proposed the use of solution stirring during the growth of protein crystals using the Micro-Stirring technique with a rotary shaker. In this paper, we report on the effects of a new type solution flow on the crystallization of hen egg-white lysozyme (HEWL) using a wave shaker. The time required for nucleation was reduced by wave stirring, but increased by rotary stirring. Nucleation was stimulated by wave stirring. This result indicates that protein crystal growth in a stirred solution is strongly dependent on the stirring method used and the solution flow. Therefore, optimized stirring conditions are essential for producing high-quality protein crystals.

  20. 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.

  1. The controversial sun

    NASA Technical Reports Server (NTRS)

    Ulrich, Roger K.

    1993-01-01

    The sun serves as an important test case for a variety of problems related to stellar structure and evolution as well as fundamental physics. The sun also influences the terrestrial environment through its varied outputs. These two aspects of the solar interior combine to generate a surprising level of controversy for such an inherently simple star. I review three topics each of which is the subject of some degree of controversy: 1) the solar neutrino problem, 2) the status of modeling and observational efforts to understand the solar cycle of activity, and 3) observational efforts to detect and identify solar g-modes.

  2. Students' Conceptions of Controversial Knowledge.

    ERIC Educational Resources Information Center

    Nicholls, John G.; Nelson, J. Ron

    1992-01-01

    Five boys and five girls each in grades one through six (n=60 students) asked controversial questions in interviews, recognized the lack of social consensus on the controversial topics and made subtle distinctions between controversial and noncontroversial topics. Implications for discussion of controversial issues in the classroom are discussed.…

  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. A Rhetoric of Controversy.

    ERIC Educational Resources Information Center

    Phillips, Kendall R.

    1999-01-01

    Contributes to scholarship advancing the understanding of human communication by exploring the concept of controversy within a theoretical framework which does not presume the existence of a public sphere. Suggests an alternative perspective based on the intersection of moments of opportunity and specific sites of discourse. Applies this…

  5. Trending Cardiovascular Nutrition Controversies.

    PubMed

    Freeman, Andrew M; Morris, Pamela B; Barnard, Neal; Esselstyn, Caldwell B; Ros, Emilio; Agatston, Arthur; Devries, Stephen; O'Keefe, James; Miller, Michael; Ornish, Dean; Williams, Kim; Kris-Etherton, Penny

    2017-03-07

    The potential cardiovascular benefits of several trending foods and dietary patterns are still incompletely understood, and nutritional science continues to evolve. However, in the meantime, a number of controversial dietary patterns, foods, and nutrients have received significant media exposure and are mired by hype. This review addresses some of the more popular foods and dietary patterns that are promoted for cardiovascular health to provide clinicians with accurate information for patient discussions in the clinical setting.

  6. Controversies in Gender Diagnoses.

    PubMed

    Drescher, Jack

    2014-03-01

    This article presents the author's thoughts on gender diagnosis controversies during his tenure at the DSM-5 Workgroup on Sexual and Gender Identity Disorders and the ICD-11 Working Group on the Classification of Sexual Disorders and Sexual Health. The work summarizes some of the published conclusions of the DSM-5 and ICD-11 revision processes regarding three particular controversies: (1) stigma versus access to care; (2) the retention of a child gender diagnosis; and (3) the treatment of prepubescent transgender children. Both the DSM and ICD work groups decided that despite the stigma associated with a diagnosis, retaining an adolescent and adult gender diagnosis is necessary to maintain access to care. As for the child gender diagnosis, given the heterogeneity of this clinical population and that gender dysphoria does not persist in most children, a child diagnosis of Gender Dysphoria (DSM) and Gender Incongruence (ICD) should be retained to facilitate ongoing evaluation and management in childhood while acknowledging the uncertainty of the outcome. The treatment of extremely gender variant prepubescent children remains a controversial subject since some underlying assumptions of the treating clinicians are a matter of opinion rather than of empirical data.

  7. 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.

  8. The breast implant controversy.

    PubMed

    Cook, R R; Harrison, M C; LeVier, R R

    1994-02-01

    The breast implant issue is a "bad news/good news" story. For many women with implants, the controversy has caused a fair degree of anxiety which may or may not be resolved as further information becomes available. It has also taken its toll on Dow Corning. Whole lines of medical products have been eliminated or are being phase out. The development of new medical applications has been terminated. As a consequence, employees have lost their jobs. What the effect will be on the biomedical industry as a whole remains to be seen (11). While silicones have been an important component in various medical devices, it is likely that other materials can be used as replacements. However, suppliers of non-silicone materials are also reevaluating their role in this market. For example, Du Pont, the nation's largest chemical company, has determined that the unpredictable and excessive costs of doing business with manufacturers of implantable medical devices no longer justifies the unrestricted sale of standard raw materials into this industry. Other companies are quietly following suit. On the up side, it is possible that the research being driven by this controversy will result in a greater understanding of the immunologic implications of xenobiotics, of the importance of nonbiased observations, of the need for ready access to valid data sets, and of the opportunity for valid scientific information to guide legal decisions. Only time will tell.

  9. Controversies in Cardioembolic Stroke

    PubMed Central

    Wessler, Benjamin S.; Kent, David M

    2015-01-01

    Opinion statement Cardioembolic (CE) stroke mechanisms account for a significant number of ischemic strokes however the true burden is likely underestimated. It is critically important to identify patients with CE strokes since these individuals have high recurrence rates and represent a subgroup of patients who may benefit from targeted therapy in the form of anticoagulation or device based treatments. Current guidelines offer recommendations for diagnosis and treatment of these patients however important questions remain. Appropriate cardiac testing in the setting of CE must be individualized and the optimal duration of electrocardiographic monitoring to rule out atrial fibrillation (AF) is unclear. So too, risk stratification tools for AF remain understudied and there is controversy about which anticoagulant agents are most appropriate. Lastly, important potential CE sources of stroke such as PFO have garnered significant attention recently and debate regarding how to treat these patients remains. In this review we discuss some of the important controversies in diagnosing and treating patients with possible CE stroke, pointing to areas where future research might be particularly valuable. PMID:25398426

  10. The bellerophont controversy revisited

    USGS Publications Warehouse

    Harper, J.A.; Rollins, H.B.

    2000-01-01

    An old controversy reestablished itself in the late 1970s and early 1980s that focused on the systematic placement of the enigmatic Bellerophontoidea (informally, "bellerophonts"), a group of planispirally coiled, wholly fossil molluscs. The controversy embraced three fundamental concepts that are based on different philosophical interpretations of shell form, muscle scar patterns, and other preserved shell features: 1) all bellerophonts were monoplacophorans; 2) all bellerophonts were gastropods; and 3) some bellerophonts were monoplacophorans and some were gastropods. A review of the main issues appearing in the literature since the early 1980s indicates that these three philosophical divisions still exist and, indeed, have become entrenched. An examination of the relevant anatomical and shell features of recent gastropods and monoplacophorans, and comparison with preserved features in enigmatic fossil forms, convinces us that the bellerophontoideans and the coiled and high-domed "monoplacophorans" (Cyclomya) were gastropods. Only the flattened, spoon-and cap-shaped monoplacophorans (Tergomya) were true monoplacophorans. We present a hypothetical scheme for the morphological diversification of gastropods from early monoplacophorans that could account for Cyclomya, Bellerophontoidea, Patellogastropoda, and Prosobranchia.

  11. 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.

  12. 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

  13. 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.

  14. Peak Stir Zone Temperature During Friction Stir Processing

    DTIC Science & Technology

    2010-03-01

    processing (FSP) and friction stir welding ( FSW ) are allied technologies involving local- ized severe plastic deformation induced by the action of a...nonconsumable tool on a deformable material. In both FSP and FSW , the tool generally consists of a cylindrical shoulder portion with a projecting, concen- tric...macroscopic shape change.[2,3] Heating during FSP/ FSW is due to a combination of adiabatic deformation in a volume of material surround- ing the tool pin

  15. 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…

  16. 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…

  17. Youth Violence. Current Controversies Series.

    ERIC Educational Resources Information Center

    Biskup, Michael D., Ed.; Cozic, Charles P., Ed.

    The Current Controversies series explores many social, political, and economic controversies, presenting the discussions in debate format. This volume focuses on youth violence. As youth violence escalates, concern grows over the safety of the neighborhoods, the victims of violence, and the future of violent youths themselves. The 35 selections in…

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Stirring properties of vortex rings

    NASA Astrophysics Data System (ADS)

    Auerbach, David

    1991-05-01

    Ring vortex evolution, from the initial roll-up phase through to the final turbulent phase, was experimentally studied to see the dependence of its stirring properties on both the initial (accelerating, constant, decelerating, slow, fast) piston motion as well as on the boundary (tube/hole geometry) conditions. Stirring between fluid initially upstream and that initially downstream of the nozzle plane is done more by convective entrainment at the beginning (roll-up and contraction phases), by diffusive entrainment during the laminar and wavy phases, and by mixed entrainment and ejection during the transition to turbulence and the turbulent phase itself. During vortex roll-up, it was found that tubes eject shorter streaklines than do holes, and that there is less Re dependence for this for tubes than for holes. During the contraction phase, entrainment ends, save for minimal entrainment due to axial inflow into the ring from along the cores of Goertler-type vortices. Generally, the rate of fluid ejected is largest during the transition from the wavy to the turbulent state. As far as the stability of the vortices is concerned, rings generated at holes are less stable than those generated at tubes. During the final turbulent phase, rings not only entrain fluid but eject it periodically into the wake: Between two and four hairpin vortices are generated and laid off in the wake during each ejection. The frequency at which such ejections takes place scales as a Strouhal number that takes on values of between 2 and 4.

  7. 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.

  8. 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.

  9. 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.

  10. 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.…

  11. 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…

  12. 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…

  13. INSTITUTIONAL POLICIES ON CONTROVERSIAL TOPICS.

    ERIC Educational Resources Information Center

    DUTTON, THOMAS B.; AND OTHERS

    THIS STUDY WAS DESIGNED TO DETERMINE INSTITUTIONAL POLICIES WITH REGARD TO SELECTED CONTROVERSIAL TOPICS WHICH ARE FREQUENTLY THE FOCUS OF ADMINISTRATIVE CONCERN AND ACTION. THE STUDY WAS DESIGNED TO GAIN INFORMATION ABOUT THE NATURE AND PURPOSES OF THE POLICIES, THE FORMULATION AND IMPLEMENTATION PROCESSES, AND THE SIGNIFICANCE OF THE ISSUES ON…

  14. 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.…

  15. Introducing Ethics Using Structured Controversies

    ERIC Educational Resources Information Center

    Wareham, David; Elefsiniotis, Takis P.; Elms, David

    2006-01-01

    This paper describes a method of introducing ethics to a second-year class of civil engineering students. The method, known as a "structured controversy", takes the form of a workshop where the students assume the identity of stakeholders having an interest in a proposed development in an environmentally sensitive region. The instructor…

  16. 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,…

  17. 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,…

  18. 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…

  19. 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)…

  20. 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…

  1. 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

  2. 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.

  3. 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.

  4. The controversial world of sirtuins.

    PubMed

    Dang, Weiwei

    2014-06-01

    The controversy around sirtuins and their functions in aging has drawn in the past few years as much attention, if not more, from the scientific community and the public as they did when first proposed as the key conserved aging regulators in eukaryotes. With some of the basic observations on sirtuin longevity promoting functions being questioned in popular model systems, researchers are wondering if this family of conserved enzymes still holds strong potential as therapeutic targets. This review examines the several controversial issues around sirtuins and their functions in aging, calorie restriction, as well as age-related diseases in light of recent studies in mammalian systems and discusses whether modulators of sirtuins still hold the secret of life.:

  5. Controversies in neurosciences critical care.

    PubMed

    Chang, Tiffany R; Naval, Neeraj S; Carhuapoma, J Ricardo

    2012-06-01

    Neurocritical care is an evolving subspecialty with many controversial topics. The focus of this review is (1) transfusion thresholds in patients with acute intracranial bleeding, including packed red blood cell transfusion, platelet transfusion, and reversal of coagulopathy; (2) indications for seizure prophylaxis and choice of antiepileptic agent; and (3) the role of specialized neurocritical care units and specialists in the care of critically ill neurology and neurosurgery patients.

  6. 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.

  7. 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)

  8. 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.

  9. 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

  10. The evolution of controversial issues.

    PubMed

    King, P

    1994-04-01

    The controversial issues concerning the differences of opinion about the validity of Melanie Klein's theory and technique did not arise suddenly when members of the Viennese Society joined the British Psycho-Analytical Society, before the outbreak of the Second World War. In this paper, I describe briefly the socio-historical, administrative and institutional background out of which these scientific divergences evolved alongside other issues concerned with how long members should hold office in the British Psycho-Analytical Society and therefore be in a position to influence the scientific disagreements and training policy in the Society. These causes for concern among members, which were discussed at five business meetings, are then summarised: they relate to differences of opinion with regard to Melanie Klein's contributions to psychoanalysis, the need for revision of the rules of the Society and the type of training in psychoanalysis that should be offered to candidates. Finally, proposals for different ways of exploring and perhaps dealing with these issues are discussed, including the decision to hold formal scientific discussions of Klein's point of view, once a month. These meetings are now referred to as the 'Controversial Discussions'.

  11. 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.

  12. 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

  13. The continuous production of stir cast material

    NASA Astrophysics Data System (ADS)

    Hamoen, A.

    1986-06-01

    The production of AlSi8 extrusion billets using a semicontinuous caster is described. The continuous casting process and the process parameters are outlined. The mathematical model, developed to calculate the temperature distribution within the billet during casting as a function of the process parameters, is explained. Quality control focussed on inversion segregation which causes the formation of a surface layer with a different structure and composition, imposing peeling of billets. Product development focussed on the production of stir-cast material of the same AlSi8 alloy. The use of AlSi8 as a wrought alloy by modification of the structure by stirring is discussed.

  14. 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.

  15. 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

  16. Control of Protein Crystal Nucleation and Growth Using Stirring Solution

    NASA Astrophysics Data System (ADS)

    Niino, Ai; Adachi, Hiroaki; Takano, Kazufumi; Matsumura, Hiroyoshi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

    2004-11-01

    We have previously developed a protein crystallization technique using a stirring protein solution and revealed that (i) continuous stirring prevents excess spontaneous nucleation and accelerates the growth of protein crystals and (ii) prestirring (solution stirring in advance) promotes the crystal nucleation of hen egg-white lysozyme. In bovine adenosine deaminase (ADA) crystallization, continuous stirring improves the crystal quality but elongates the nucleation time. In this paper, in order to control both the crystal nucleation and growth of ADA using a Micro-Stirring technique, we carried out five different stirring patterns such as (i) no stirring, (ii) continuous stirring, (iii) prestirring, (iv) poststirring (stirring late in the growth period) and (v) restirring (combined pre- and poststirring). The results showed that high-quality well-shaped crystals were obtained under the continuous stirring and restirring conditions and the nucleation time under the prestirring and restirring conditions was shorter than that under the continuous stirring and poststirring conditions. Consequently, high-quality crystals were promptly obtained under the restirring condition. These results suggest that we are able to control both the nucleation and growth of protein crystals with the stirring techniques.

  17. 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…

  18. Friction Stir & Ultrasonic Solid State Joining Magnesium

    SciTech Connect

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

    2009-12-30

    Solid state joining between automotive sheet steel and magnesium alloys was investigated. Both friction stir welding and ultrasonic welding were utilized to study the potential for creating structural bonds between these dissimilar materials. A detailed investigation into the joint characteristics was undertaken including an evaluation of joint strength, microstructure, chemical structures, and alloy formation.

  19. The Parkfield Stress Drop Controversy

    NASA Astrophysics Data System (ADS)

    Abercrombie, R. E.; Nadeau, R. M.

    2003-12-01

    Nadeau et al. (1995) found that the seismicity on the San Andreas fault at Parkfield is highly clustered. Individual clusters consist of a sequence of near periodically repeating small earthquakes of similar seismic moment. Nadeau and Johnston (1998) compared the moments and timing of these repeating earthquakes (Mw < 2), and some larger events, with the surface creep rate on the fault to estimate the slip and stress drop (Δ σ ). They obtained conventional values (0.1 to 10 MPa) for the larger earthquakes, but Δ σ increased with decreasing Mw to extremely high values (> 1000 MPa) for the small earthquakes (Mw < 2). Such values are just about physically possible, but they are much higher than those estimated by seismic methods for small earthquakes elsewhere (e. g. Abercrombie 1995). These controversial high Δ σ estimates have sparked a number of theoretical and laboratory studies (e. g. Sammis & Rice 2000, Anooshepoor & Brune 2001, Beeler 2001) aimed at investigating whether the observations could result from earthquakes with more normal Δ σ occurring within the unusual tectonic setting at Parkfield. Lane & Nadeau (2000, 2002) considered whether localized patches of high Δ σ would be resolvable by standard seismic methods. However, to date nobody has used seismic methods to determine source parameters for these controversial small earthquakes at Parkfield. We use closely located earthquakes of different sizes (for example, the sub-clusters of cluster CL14, Nadeau et al., 1995, Mw-0.2 to 1), recorded on the HRSN borehole network to analyse the source parameters. The smaller earthquakes are used as empirical Green's functions to resolve source processes of the larger events. Preliminary results from the earthquakes in cluster CL14 result in a source dimension of about 25 m and Δ σ of about 1 MPa for the Mw1 earthquakes, assuming that rupture velocity is the same as that for large earthquakes. We also resolve source-time functions for these earthquakes at

  20. The HPV vaccine mandate controversy.

    PubMed

    Haber, Gillian; Malow, Robert M; Zimet, Gregory D

    2007-12-01

    In this editorial we address the controversies surrounding human papillomavirus (HPV) vaccine school-entry mandate legislation, but differentiate between the mandate debate and issues specific to the vaccine itself. Our goal is not to take a stand in favor of or opposed to mandates, but rather to critically examine the issues. We discuss the following arguments against HPV vaccine school-entry requirements: 1. The public health benefit of mandated HPV vaccination is not sufficient to warrant the intrusion on parental autonomy; 2. A vaccine that prevents a non-casually transmitted infection should not be mandated; 3. Opt-out provisions are inherently unfair to parents who oppose HPV vaccination; 4. Limited health care dollars should not be directed toward cervical cancer prevention; and 5. The vaccine is expensive and potential problems with supply suggest that mandates should not be implemented until insurance coverage and supply issues are resolved. Next, we critically evaluate the following critiques of HPV vaccination itself: 1. Giving girls HPV vaccine implies tacit consent to engage in sexual activity; 2. Giving girls this vaccine will confer a false sense of protection from sexually transmitted infections and will lead to sexual disinhibition; 3. Children already have too many vaccinations on the immunization schedule; 4. Long-term side effects of HPV vaccine are unknown; 5. The vaccine's enduring effectiveness is unknown and booster shots may be required; and 6. It is wrong to only target girls with HPV vaccine; boys should be vaccinated as well.

  1. 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

  2. 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.

  3. [Controversy on treatments for gliomas].

    PubMed

    Nomura, K

    1998-09-01

    Gliomas are representative primary malignant brain tumors, and with such tumors it is difficult to define the advanced stage. If the advanced stage indicates no curability by surgery alone, most gliomas would belong to this criterion because of their poor prognosis without any completely effective treatment. In this sense, no one could show a standard therapy to treat these unfortunate patients, for example, patients with glioblastoma, they could permit only 1 year survived even they had any applicable treatments to the lesions, these days. Treatment for low-grade gliomas has been most controversial for a long time, and no standard treatments have been determined so far. In this paper, as the treatment of low-grade gliomas it was intended to report what must be done for this patient and the present results of opinion survey for the treatment of gliomas which was done to professors of 80 institutes, from schools of medicine at all universities and medical colleges in Japan. For high-grade gliomas, some effectiveness of radiation therapy was disclosed as well as chemotherapy from recent papers. Gene therapy was also discussed briefly, its present status and future.

  4. Lyme disease: why the controversy?

    PubMed

    Beaman, M H

    2016-12-01

    Some Australians have become convinced of the existence of locally acquired Lyme disease (LD). The history of LD, since its recognition in the early 1970s, is reviewed as a model for investigative approaches to unknown syndromes. Australian Management Guidelines for LD include the requirement for diagnostic testing by National Association of Testing Authorities-accredited laboratories using Therapeutic Goods Administration-licensed tests, which result in the efficient diagnosis of LD in overseas travellers. Despite this, patients who have not left Australia pay many thousands of dollars for non-specialist consultations and testing at overseas laboratories. Unproven long-term therapy with multiple antibiotics has resulted in serious complications, including allergies, line sepsis, pancreatitis and pseudomembranous colitis. Studies have shown that LD vectors are not found in Australia, and Lyme Borrelia has not been found in Australian vectors, animals or patients with autochthonous illnesses. I propose that (i) A non-controversial name for the chronic syndrome should be adopted, 'Australian Multisystem Disorder'. (ii) Research funding should enable the development of a consensus case definition and studies of the epidemiology of this syndrome with laboratory investigations to identify an aetiology and surrogate markers of disease. Prospective, randomised treatment studies could then be undertaken using ethical protocols.

  5. 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.

  6. 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.

  7. Effects of Solution Stirring on Protein Crystal Growth

    NASA Astrophysics Data System (ADS)

    Yaoi, Mari; Aadachi, Hiroaki; Takano, Kazufumi; Matsumura, Hiroyoshi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

    2004-05-01

    We report the influence of solution stirring on the growth of hen egg white lysozyme crystals. Solution stirring rate was controlled by varying the rotation speed of a rotary shaker. A range of precipitation agent (sodium chloride) concentrations was also investigated. The time required for crystal nucleation to occur was observed to be much greater in stirred samples than in unstirred samples. Solution stirring resulted in a reduced number of crystals (at sodium chloride concentrations from 6 to 9%). These crystals were larger and of a higher quality. However, the time required for nucleation to occur was reduced by gentle stirring (25 and 50 rpm) in a 12.5% sodium chloride concentration solution, suggesting that stirring can stimulate nucleation. These results indicate that the optimization of solution stirring rates is a useful technique for controlling protein crystal growth.

  8. [Controversies over heel pressure ulcers].

    PubMed

    Rueda López, J

    2013-02-01

    Article whose content was exposed in the workshops of the GNEAUPP Congress, held in Seville in November2012, and which refers to ulcers by pressure on the heels as a location exposed to the analysis. A pressure ulcer is a lesion located in skin I underlying tissue usually over a bone prominence, as a result of the pressure, or pressure in combination with the shears. A number of contributing factors or confounding factors are also associated with ulcers by pressure; the importance of these factors still not been elucidated. The heels are next to the sacred area, parts of the body that most frequently presents ulcers by pressure, The importance of the predisposing factors for ulcers in the sacral area as humidity has been studied in recent years, but in heels, remains one of the most important locations in the extremities, which entails adverse outcomes such as amputation in persons with comorbid diseases like Diabetes Mellitus (DM). The incidence of ulcers on heels in patients with DM and without it, is approximately 19-32%. Everything and be a problem associated with elderly people and chronic pathologies, in acute patients are a problem that this underrated, but not devoid of controversy. In hospitals of treble in 2006, the NPUAP encrypted the incidence of UPPin heels in a 43%; in one systematic review conducted by Reddy et al. (2006) puts revealed that 60% of pressure ulcers is produced. The problem of the UPP in heels is present in all the areas of intervention and particularly in paediatric units intensive care, where the first localization it is the occipital area followed by the heels.

  9. If It's Controversial, Why Teach It?

    ERIC Educational Resources Information Center

    Soley, Mary

    1995-01-01

    Reveals that teaching about controversial issues increases students' self-confidence and interest in civic participation. Asserts that the current proliferation of social problems combined with exploitative media coverage necessitates civil and objective study of controversial issues. Includes several examples of, and approaches to, teaching about…

  10. 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)

  11. 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…

  12. 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…

  13. 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…

  14. 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…

  15. "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…

  16. Salivary Gland Tumors: Current Concepts and Controversies.

    PubMed

    Seethala, Raja R

    2017-03-01

    This current review focuses on current concepts and controversies for select key salivary gland epithelial neoplasms. Rather than the traditional organization of benign and malignant tumors, this review is structured around select key topics: biphasic tumors, mammary analogue secretory carcinoma, and the controversy surrounding polymorphous low-grade adenocarcinoma and cribriform adenocarcinoma of (minor) salivary gland origin.

  17. 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)

  18. Deciding What Is a Controversial Issue: A Case Study of Social Studies Curriculum Controversy

    ERIC Educational Resources Information Center

    Camicia, Steven P.

    2008-01-01

    Frame analysis was used to examine how competing stakeholders framed a sixth grade curriculum controversy over whether the WWII internment of Japanese Americans should be categorized as a controversial issue. Teachers and administrators in a northwestern U.S. school claimed that the internment was clearly wrong and not controversial, but these…

  19. 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.

  20. 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.

  1. 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.

  2. Magnesium Based Composite via Friction Stir Processing

    DTIC Science & Technology

    2013-04-01

    process developed by Mishra et.al [8] based on the principles of friction stir welding ( FSW ) is getting increased attention. It involves the traverse...compared to other thermomechanical processes [9]. Mishra et al. [10] have used FSP to fabricate a surface composite with SiC particulates in aluminum ...This work was followed by other reports of composite fabrication in aluminum alloys with various reinforcements, like Al3Ti, Al2Cu, Al2O3

  3. 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.

  4. 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.

  5. Stir bar sorptive extraction for trace analysis.

    PubMed

    David, Frank; Sandra, Pat

    2007-06-08

    Stir bar sorptive extraction (SBSE) was introduced in 1999 as a solventless sample preparation method for the extraction and enrichment of organic compounds from aqueous matrices. The method is based on sorptive extraction, whereby the solutes are extracted into a polymer coating on a magnetic stirring rod. The extraction is controlled by the partitioning coefficient of the solutes between the polymer coating and the sample matrix and by the phase ratio between the polymer coating and the sample volume. For a polydimethylsiloxane coating and aqueous samples, this partitioning coefficient resembles the octanol-water partitioning coefficient. In comparison to solid phase micro-extraction, a larger amount of sorptive extraction phase is used and consequently extremely high sensitivities can be obtained as illustrated by several successful applications in trace analysis in environmental, food and biomedical fields. Initially SBSE was mostly used for the extraction of compounds from aqueous matrices. The technique has also been applied in headspace mode for liquid and solid samples and in passive air sampling mode. In this review article, the principles of stir bar sorptive extraction are described and an overview of SBSE applications is given.

  6. Stirring effects in models of oceanic plankton populations

    NASA Astrophysics Data System (ADS)

    Neufeld, Zoltan

    2012-09-01

    We present an overview and extend previous results on the effects of large scale oceanic transport processes on plankton population dynamics, considering different types of ecosystem models. We find that increasing stirring rate in an environment where the carrying capacity is non-uniformly distributed leads to an overall decrease of the effective carrying capacity of the system. This may lead to sharp regime shifts induced by stirring in systems with multiple steady states. In prey-predator type systems, stirring leads to resonant response of the population dynamics to fluctuations enhancing the spatial variability—patchiness—in a certain range of stirring rates. Oscillatory population models produce strongly heterogeneous patchy distribution of plankton blooms when the stirring is weak, while strong stirring may either synchronise the oscillatory dynamics, when the inhomogeneity is relatively weak, or suppress oscillations completely (oscillator death) by reducing the effective carrying capacity below the bifurcation point.

  7. Stirring effects in models of oceanic plankton populations.

    PubMed

    Neufeld, Zoltan

    2012-09-01

    We present an overview and extend previous results on the effects of large scale oceanic transport processes on plankton population dynamics, considering different types of ecosystem models. We find that increasing stirring rate in an environment where the carrying capacity is non-uniformly distributed leads to an overall decrease of the effective carrying capacity of the system. This may lead to sharp regime shifts induced by stirring in systems with multiple steady states. In prey-predator type systems, stirring leads to resonant response of the population dynamics to fluctuations enhancing the spatial variability-patchiness-in a certain range of stirring rates. Oscillatory population models produce strongly heterogeneous patchy distribution of plankton blooms when the stirring is weak, while strong stirring may either synchronise the oscillatory dynamics, when the inhomogeneity is relatively weak, or suppress oscillations completely (oscillator death) by reducing the effective carrying capacity below the bifurcation point.

  8. Corrosion Behavior of Friction Stir Welded High Strength Aluminum Alloys

    DTIC Science & Technology

    2002-01-18

    Angelo Guinasso, " Stress Corrosion Susceptibility in 7050 -T751 Aluminum Following Friction Stir Welding", Proc. First Friction Stir Welding Symposium...potential of the nugget. Susceptibility to stress corrosion cracking (SCC) was evaluated using the slow strain rate (SSR) method described in ASTM Standards...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP015941 TITLE: Corrosion Behavior of Friction Stir Welded High Strength

  9. Microstructural Evolution in Friction Stir Welding of Ti-5111

    DTIC Science & Technology

    2010-08-01

    industry for aluminum alloys. FSW of steels is under continued development. 1.1.3.1 Friction Stir Welding of Metals Since the development of...or friction welding [Titanium handbook]. A potential welding technique for titanium that has shown promise for joining aluminum and steel is...combatants, this research examines an alternative joining technology, friction stir welding ( FSW ). Friction stir welding uses a non-consumable tool to

  10. 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.

  11. 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)

  12. 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)

  13. Anti-aging cosmetics: facts and controversies.

    PubMed

    Ramos-e-Silva, Marcia; Celem, Livia Ribeiro; Ramos-e-Silva, Stella; Fucci-da-Costa, Ana Paula

    2013-01-01

    The authors review ageing in its extrinsic and intrinsic mechanisms, as well as the therapies available for improving its effects, and present some of the facts and controversies related to anti-aging cosmetics.

  14. Antidote to Controversy? Responses to Carolyn Henly.

    ERIC Educational Resources Information Center

    Randall, Mary Ella; And Others

    1993-01-01

    Provides four practicing teachers' written responses to Carolyn Henly's article entitled "Reader Response Theory as Antidote to Controversy: Teaching "The Bluest Eye," which appears in the same issue. (HB)

  15. Controversies in Persistent (Chronic) Lyme Disease

    PubMed Central

    2016-01-01

    The Centers for Disease Control and Prevention estimates that more than 300 000 new cases of Lyme disease occur each year in the United States and that 10% to 20% of these patients will remain symptomatic despite receiving appropriate antibiotic therapy. Many elements of the disease are poorly understood and have generated considerable controversy. This paper discusses the medical controversies related to posttreatment manifestations and their potential impact on infusion nurses. PMID:27755213

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

    PubMed

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

    2016-05-06

    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.

  17. 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.

  18. Forming of aluminium alloy friction stir welds

    NASA Astrophysics Data System (ADS)

    Bruni, Carlo

    2016-10-01

    The present paper aims at investigating, through analytical models, numerical models and experiments, the effect of the warm deformation phase, realised with an in temperature upsetting, on the weld previously performed by friction stir lap welding on aluminium alloy blanks. The investigation allows to show the deformation zones after upsetting that determine the homogenisation of the weld section. The analytical model allows to relate the friction factor with the upsetting load. The presence on the weld of not elevated friction factor values determines the deformation and localisation levels very useful for the weld. Such methodology allows to improve the weld itself with the forming phase.

  19. Gas fluidized-bed stirred media mill

    DOEpatents

    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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Improving the Quality of Protein Crystals Using Stirring Crystallization

    NASA Astrophysics Data System (ADS)

    Adachi, Hiroaki; Matsumura, Hiroyoshi; Niino, Ai; Takano, Kazufumi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

    2004-04-01

    Recent reports state that a high magnetic field improves the crystal quality of bovine adenosine deaminase (ADA) with an inhibitor [Kinoshita et al.: Acta Cryst. D59 (2003) 1333]. In this paper, we examine the effect of stirring solution on ADA crystallization using a vapor-diffusion technique with rotary and figure-eight motion shakers. The probability of obtaining high-quality crystals is increased with stirring in a figure-eight pattern. Furthermore, rotary stirring greatly increased the probability of obtaining high-quality crystals, however, nucleation time was also increased. The crystal structure with the inhibitor was determined at a high resolution using a crystal obtained from a stirred solution. These results indicate that stirring with simple equipment is as useful as the high magnetic field technique for protein crystallization.

  12. Grain misorientation in thixo-billets prepared by melt stirring

    SciTech Connect

    Nafisi, S.; Szpunar, J.; Vali, H.; Ghomashchi, R.

    2009-09-15

    For semi solid metal (SSM) slurries, in addition to the morphology, size, distribution and percentage of the solid phase particles, the microstructure of individual solid particles is another important parameter to be considered. This is particularly an issue when SSM billets are prepared by continuous stirring of the melt to temperatures below liquidus, as in the case of electromagnetic stirring of Al-Si alloys. Microstructural evolution of the electromagnetically stirred Al-Si alloy is investigated by means of optical and electron microscopy. Electron backscatter diffraction (EBSD) analysis of the stirred and unstirred cast billets has shown stirring to generate local misorientation within individual solid particles. This is an indication of growing dendrites undergoing plastic deformation during the course of SSM slurry preparation. The formation of dislocations and their subsequent rearrangement into subgrain boundaries has been shown by EBSD analysis and TEM studies of thin foil specimens respectively.

  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. Effect of stirring and seeding on whey protein fibril formation.

    PubMed

    Bolder, Suzanne G; Sagis, Leonard M C; Venema, Paul; van der Linden, Erik

    2007-07-11

    The effect of stirring and seeding on the formation of fibrils in whey protein isolate (WPI) solutions was studied. More fibrils of a similar length are formed when WPI is stirred during heating at pH 2 and 80 degrees C compared to samples that were heated at rest. Addition of seeds did not show an additional effect compared to samples that were stirred. We propose a model for fibril formation, including an activation, nucleation, growth, and termination step. The activation and nucleation steps are the rate-determining steps. Fibril growth is relatively fast but terminates after prolonged heating. Two processes that possibly induce termination of fibril growth are hydrolysis of nonassembled monomers and inactivation of the growth ends of the fibrils. Stirring may break up immature fibrils, thus producing more active fibrils. Stirring also seems to accelerate the kinetics of fibril formation, resulting in an increase of the number of fibrils formed.

  15. 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.

  16. Calling controversy: assessing synthetic biology's conflict potential.

    PubMed

    Torgersen, Helge; Hampel, Jürgen

    2012-02-01

    Will synthetic biology elicit controversies similar to those of genetically modified crops before? Maybe, but where exactly are the analogies, and how can we gain substantial insights rather than mere guesses? We argue that as well as the intrinsic properties of the technologies at stake, the context of their implementation is decisive. To assess mechanisms of past and potential controversies, an investigative tool is presented. The Gate Resonance model, derived from older models of societal conflict, allows the identification of key elements of conflict generating processes. In monitoring the developing debate on synthetic biology using this model, analogies to the case of genetically modified crops appear less convincing. So far, there are only few indications that a controversy is imminent.

  17. What price politics? Scientists and political controversy.

    PubMed

    Nye, M J

    1999-01-01

    There is a long tradition within scientific communities that encourages governments, patrons and citizens to enlist scientific expertise in the service of the public good. However, since the 17th century, scientists who have engaged in public political controversy have often been judged harshly by scientific colleagues, as well as by political adversaries. Some prominent scientists were politically active in Germany, France and England during the 1920s and 1930s; controversial stands were taken by the British physicist P.M.S. Blackett and the American chemist Linus C. Pauling against their countries' nuclear weapons policy following the Second World War.

  18. 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

  19. '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.

  20. 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…

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. In-process discontinuity detection during friction stir welding

    NASA Astrophysics Data System (ADS)

    Shrivastava, Amber

    The objective of this work is to develop a method for detecting the creation of discontinuities (e.g., voids) during friction stir welding. Friction stir welding is inherently cost-effective, however, the need for significant weld inspection can make the process cost-prohibitive. A new approach to weld inspection is required -- where an in-situ characterization of weld quality can be obtained, reducing the need for post-process inspection. Friction stir welds with discontinuity and without discontinuity were created. In this work, discontinuities are generated by reducing the friction stir tool rotation frequency and increasing the tool traverse speed in order to create "colder" welds. During the welds, forces are measured. Discontinuity sizes for welds are measured by computerized tomography. The relationship between the force transients and the discontinuity sizes indicate that the force measurement during friction stir welding can be effectively used for detecting discontinuities in friction stir welds. The normalized force transient data and normalized discontinuity size are correlated to develop a criterion for discontinuity detection. Additional welds are performed to validate the discontinuity detection method. The discontinuity sizes estimated by the force measurement based method are in good agreement with the discontinuity sizes measured by computerized tomography. These results show that the force measurement based discontinuity detection model method can be effectively used to detect discontinuities during friction stir welding.

  6. 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…

  7. 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.

  8. 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…

  9. Controversial natural gas and oil issues tackled

    SciTech Connect

    Rodgers, L.M.

    1991-04-15

    This article reports on recent activities regarding controversial natural gas and oil issues including the strategic oil reserve, expanded access to drilling in the outer continental shelf and authorization of oil and gas leasing in the Arctic National Wildlife Refuge, reestablishing regulation of the natural gas industry and budgeting for research and development.

  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. 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,…

  12. 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)

  13. Controversial Art in the Community College.

    ERIC Educational Resources Information Center

    Hom, Bobby

    This document examines the events surrounding a controversial art exhibit that was held at Santa Fe Community College (SFCC), Gainesville, Florida, in 2002. The author asks the following questions: (1) What is the role of the arts on a community college campus? (2) What are a community college arts program's responsibilities to the Fine Arts and…

  14. Bones of Contention: Teaching Controversial Issues

    ERIC Educational Resources Information Center

    Hinde, Elizabeth

    2004-01-01

    Dealing with contentious issues is a part of living in a democracy. Controversies in the classroom range from discussions of fairness regarding playground rules to the rules of "just war." Understanding that there are multiple and often competing viewpoints is a prerequisite to being an informed and effective citizen. Teaching students to define…

  15. 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…

  16. 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…

  17. 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…

  18. 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...

  19. 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)

  20. 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 §...

  1. 30 CFR 281.9 - Jurisdictional controversies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 2 2011-07-01 2011-07-01 false Jurisdictional controversies. 281.9 Section 281.9 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, REGULATION, AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF MINERALS OTHER THAN OIL, GAS, AND SULPHUR IN THE OUTER...

  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. 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…

  4. Wastewater treatment by radial freezing with stirring effects.

    PubMed

    Gay, Guillaume; Lorain, Olivier; Azouni, Aza; Aurelle, Yves

    2003-05-01

    Radial freezing experiments on wastewater models were conducted in the presence of imposed stirring in order to remove impurities. The studied samples (dilute Na-montmorillonite suspensions charged with nitrates and with zinc or lead) were placed inside a cylindrical annulus, cooled at a controlled temperature around -7 degrees C at its inner wall which rotated around a vertical axis. The freezing front propagated toward the still outer wall which was maintained at a constant temperature around +1 degrees C. Thanks to stirring, considerable purification rates up to 99.97% were attained. It was also demonstrated that combining radial freezing and stirring ended in residual concentrations which agreed with drinking water standards.

  5. 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.

  6. 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.

  7. 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

  8. Nanoemulsions produced by rotor-stator high speed stirring.

    PubMed

    Scholz, Patrik; Keck, Cornelia M

    2015-03-30

    Nanoemulsions were produced by high speed stirring using an ART MICCRA D27 rotor-stator system. Nanoemulsions with a droplet size of 135 nm and a narrow size distribution were obtained. The emulsions are physically stable for at least three months. Optimized production parameters are a stirring speed of 36,000 rpm (maximum speed) and a production time of 5 min. A further reduction in processing time might be possible with a rotor with ultrafine slit size, i.e., 0.5 mm. The droplet size of the emulsion produced by high speed stirring is slightly larger than droplet sizes obtained by high pressure homogenization. However, the differences in size can be expected to have no influence on the in vivo efficacy of the emulsions. Thus, high speed stirring was found to be a highly effective method for the production of nanoemulsions. The process is fast, cost-effective and can be used for large scale production.

  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. Erythropoietin in bone - Controversies and consensus.

    PubMed

    Hiram-Bab, Sahar; Neumann, Drorit; Gabet, Yankel

    2017-01-01

    Erythropoietin (Epo) is the main hormone that regulates the production of red blood cells (hematopoiesis), by stimulating their progenitors. Beyond this vital function, several emerging roles have been noted for Epo in other tissues, including neurons, heart and retina. The skeletal system is also affected by Epo, however, its actions on bone are, as yet, controversial. Here, we review the seemingly contradicting evidence regarding Epo effects on bone remodeling. We also discuss the evidence pointing to a direct versus indirect effect of Epo on the osteoblastic and osteoclastic cell lineages. The current controversy may derive from a context-dependent mode of action of Epo, namely opposite skeletal actions during bone regeneration and steady-state bone remodeling. Differences in conclusions from the published in-vitro studies may thus relate to the different experimental conditions. Taken together, these studies indicate a complexity of Epo functions in bone cells.

  11. Vitamin a: history, current uses, and controversies.

    PubMed

    Chapman, M Shane

    2012-03-01

    Vitamin A is required for the proper functioning of many important metabolic and physiologic activities, including vision, gene transcription, the immune system and skin cell differentiation. Both excessive and deficient levels of vitamin A lead to poor functioning of many human systems. The biologically active form, retinoic acid, binds to nuclear receptors that facilitate transcription that ultimately leads to it's physiological effects. Retinoids are derivatives of vitamin A that are medications used to treat acne vulgaris, psoriasis, ichthyosis (and other disorders of keratinization), skin cancer prevention as well as several bone marrow derived neoplasias. Systemic retinoids are teratogenic and have to be prescribed with caution and close oversight. Other potential adverse events are controversial. These include the relationship of retinoid derivatives in sunscreens, their effects on bone mineral density, depression and suicidal ideation and inflammatory bowel disease. These controversies will be discussed in detail.

  12. Epistemic Authority and Genuine Ethical Controversies.

    PubMed

    Roberts, Adam James

    2017-02-03

    In 'Professional Hubris and its Consequences', Eric Vogelstein claims that 'that there are no good arguments in favor of professional organizations taking genuinely controversial positions on issues of professional ethics'. In this response, I defend two arguments in favour of organisations taking such positions: that their stance-taking may lead to better public policy, and that it may lead to better practice by medical professionals. If either of those defences succeeds, then Vogelstein's easy path to his conclusion - that professional organisations should not take such stances - is blocked. He or others must instead look to establish that the reasons against stance-taking on genuine ethical controversies are more compelling than those for it: plausibly a more challenging task.

  13. All-inside ACL: retroconstruction controversies.

    PubMed

    Lubowitz, James H

    2010-03-01

    All-inside anterior cruciate ligament reconstruction is controversial because the technique is new; as a result, evidence-based clinical outcome studies have yet to be published. The purpose of this article is to consider the following controversies (considered alphabetically): anatomy, biomechanics, biology, bioabsorbables, divergence of the femoral interference screw, expansion or widening of tunnels, fixation, future considerations, graft choice, the learning curve, technique, tensioning, and tibia blow-out fracture. The technique should be learned in stages. In the opinion of the author, the history of sports medicine and arthroscopy has been a progression toward less invasive techniques. In the future, all-inside anterior cruciate ligament reconstruction techniques should become more simple and reproducible, and clinical outcomes must be analyzed with long-term follow-up.

  14. Cancer stem cells: controversies in multiple myeloma.

    PubMed

    Brennan, Sarah K; Matsui, William

    2009-11-01

    Increasing data suggest that the initiation, relapse, and progression of human cancers are driven by specific cell populations within an individual tumor. However, inconsistencies have emerged in precisely defining phenotypic markers that can reliably identify these "cancer stem cells" in nearly every human malignancy studied to date. Multiple myeloma, one of the first tumors postulated to be driven by a rare population of cancer stem cells, is no exception. Similar to other diseases, controversy surrounds the exact phenotype and biology of multiple myeloma cells with the capacity for clonogenic growth. Here, we review the studies that have led to these controversies and discuss potential reasons for these disparate findings. Moreover, we speculate how these inconsistencies may be resolved through studies by integrating advancements in both myeloma and stem cell biology.

  15. 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.

  16. Friction Stir Welding of Aluminum and Titanium Alloys

    DTIC Science & Technology

    2007-11-02

    What is this? Jata/US Air Force Typical FSW Tools W-Re tool in collet- style tool holder. Used for welding steels and Ti alloys 3-piece self...Friction Stir Welding of Aluminum and Titanium alloys NATO Advanced Research Workshop Metallic Materials with High Structural Efficiency Kyiv...valid OMB control number. 1. REPORT DATE 18 MAR 2004 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Friction Stir Welding of Aluminum

  17. Persistent Confusion and Controversy Surrounding Gene Patents

    PubMed Central

    Guerrini, Christi J.; Majumder, Mary A.; McGuire, Amy L.

    2016-01-01

    There is persistent confusion and controversy surrounding basic issues of patent law relevant to the genomics industry. Uncertainty and conflict can lead to the adoption of inefficient practices and exposure to liability. The development of patent-specific educational resources for industry members, as well as the prompt resolution of patentability rules unsettled by recent U.S. Supreme Court decisions, are therefore urgently needed. PMID:26849516

  18. 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.

  19. 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

  20. 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

  1. Friction Stir Welding of Curved Plates

    NASA Technical Reports Server (NTRS)

    Sanchez, Nestor

    1999-01-01

    Friction stir welding (FSW) is a remarkable technology for making butt and lap joints in aluminum alloys. The process operates by passing a rotating tool between two closely butted plates. This process generates heat and the heated material is stirred from both sides of the plates to generate a high quality weld. Application of this technique has a very broad field for NASA. In particular, NASA is interested in using this welding process to manufacture tanks and curved elements. Therefore, this research has been oriented to the study the FSW of curved plates. The study has covered a number of topics that are important in the model development and to uncover the physical process involve in the welding itself. The materials used for the experimental welds were as close to each other as we could possibly find, aluminum 5454-0 and 5456-0 with properties listed at http://matweb.com. The application of FSW to curved plates needs to consider the behavior that we observed in this study. There is going to be larger force in the normal direction (Fz) as the curvature of the plate increases. A particular model needs to be derived for each material and thickness. A more complete study should also include parameters such as spin rate, tool velocity, and power used. The force in the direction of motion (Fx) needs to be reconsidered to make sure of its variability with respect to other parameters such as velocity, thickness, etc. It seems like the curvature does not play a role in this case. Variations in temperature were found with respect to the curvature. However, these changes seem to be smaller than the effect on Fz. The temperatures were all below the melting point. We understand now that the process of FSW produces a three dimensional flow of material that takes place during the weld. This flow needs to be study in a more detailed way to see in which directions the flow of material is stronger. It could be possible to model the flow using a 2-dimensional model in the

  2. 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.

  3. PrEP: controversy, agency and ownership

    PubMed Central

    Cairns, Gus P; Race, Kane; Goicochea, Pedro

    2016-01-01

    Pre-exposure prophylaxis (PrEP) has been and continues to be an intervention that causes controversy and debate between stakeholders involved in providing or advocating for it, and within communities in need of it. These controversies extend beyond the intrinsically complex issues of making it available. In this commentary, some of the possible roots of the air of dissent and drama that accompanies PrEP are explored. The similarities between the controversies that dogged the earliest human trials of PrEP and the ones we see today in the era of licensing and implementation are explored. We outline five mediating principles or cultural norms that may influence arguments about PrEP differently. Three areas of specific concern are identified: medical risk versus benefit, distrust and fear of healthcare interventions, and fears for individual responsibility and community cohesion. The fear that PrEP may somehow represent a loss of control over one or more of these domains is suggested as an underlying factor. The development of countervailing measures, to institute greater community “ownership” of PrEP, and concomitant improvements in the sense of individual agency over sexual risk are outlined and recommended. PMID:27760689

  4. Common controversies in management of biliary strictures

    PubMed Central

    Parsi, Mansour A

    2017-01-01

    Biliary strictures are caused by a heterogeneous group of benign and malignant conditions, each requiring a specific treatment approach. Management of biliary strictures often involves endoscopy either for definite treatment, as a bridge to surgery or for palliative purposes. Endoscopic treatment of various types of biliary strictures is not standardized and there are multiple areas of controversy regarding the best treatment options. These controversies are mainly due to lack of well-designed comparative studies to support a specific therapy. This paper reviews three common areas of controversy in the endoscopic management of biliary strictures. The areas discussed in this editorial include the role of biliary drainage in resectable malignant strictures and whether such drainage should be performed routinely prior to surgery, the best endoscopic palliation for unresectable hilar strictures and whether unilateral or bilateral stenting should be attempted, and the optimal endoscopic management for dominant strictures in patients with primary sclerosing cholangitis. The goal of this editorial is twofold. The first is to review the current literature on management of the aforementioned strictures and offer recommendations based on available evidence. The second goal is to highlight the gaps in our knowledge which in turn can encourage future research on these topics. PMID:28275292

  5. 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.

  6. 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.

  7. Magnetic properties of friction stir processed composite

    SciTech Connect

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

    2016-03-29

    There are many existing inspection systems each with their own advantages and drawbacks. These usually comprise of semi-remote sensors which frequently causes difficulty in reaching complex areas of a component. This study proposes to overcome that difficulty by developing embedded functional composites. Through this route, embedding can be achieved in virtually any component part and can be periodically interrogated by a reading device. The “reinforcement rich” processed areas can then be utilized to record properties like strain, temperature, stress state etc. depending on the reinforcement material. In this work, friction stir processing (FSP) was utilized to fabricate a magnetostrictive composite by embedding galfenol particles into a nonmagnetic aluminum (Al) matrix. It targets to develop a composite that produces strain in a varying magnetic field. Reinforcements were observed to be distributed uniformly in the matrix. Magnetization curves were studied using a vibrating sample magnetometer (VSM). A simple and cheap setup was developed to measure the magnetostrictive strain of the composites. Important factors affecting the magnetic properties were identified and ways to improve the magnetic properties discussed.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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.

  19. J Wave Syndromes: History and Current Controversies

    PubMed Central

    Liu, Tong; Zheng, Jifeng

    2016-01-01

    The concept of J wave syndromes was first proposed in 2004 by Yan et al for a spectrum of electrocardiographic (ECG) manifestations of prominent J waves that are associated with a potential to predispose affected individuals to ventricular fibrillation (VF). Although the concept of J wave syndromes is widely used and accepted, there has been tremendous debate over the definition of J wave, its ionic and cellular basis and arrhythmogenic mechanism. In this review article, we attempted to discuss the history from which the concept of J wave syndromes (JWS) is evolved and current controversies in JWS. PMID:27721848

  20. Dissociative identity disorder: a controversial diagnosis.

    PubMed

    Gillig, Paulette Marie

    2009-03-01

    A brief description of the controversies surrounding the diagnosis of dissociative identity disorder is presented, followed by a discussion of the proposed similarities and differences between dissociative identity disorder and borderline personality disorder. The phenomenon of autohypnosis in the context of early childhood sexual trauma and disordered attachment is discussed, as is the meaning of alters or alternate personalities. The author describes recent neurosciences research that may relate the symptoms of dissociative identity disorder to demonstrable disordered attention and memory processes. A clinical description of a typical patient presentation is included, plus some recommendations for approaches to treatment.

  1. 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)

  2. 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

  3. Bleeding avoidance strategies. Consensus and controversy.

    PubMed

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

    2011-06-28

    Bleeding complications after coronary intervention are associated with prolonged hospitalization, increased hospital costs, patient dissatisfaction, morbidity, and 1-year mortality. Bleeding avoidance strategies is 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 suggest 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), pharmacological (multiple agents), and technological (vascular closure devices) approaches to improved access. In this paper, 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. Evolutionary psychology. Controversies, questions, prospects, and limitations.

    PubMed

    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 hypotheses that go against traditional psychological theories; some from empirical findings that may have disturbing implications; some from misunderstandings about the logic of evolutionary psychology; and some from reasonable scientific concerns about its underlying framework. This article identifies some of the most common concerns and attempts to elucidate evolutionary psychology's stance pertaining to them. These include issues of testability and falsifiability; the domain specificity versus domain generality of psychological mechanisms; the role of novel environments as they interact with evolved psychological circuits; the role of genes in the conceptual structure of evolutionary psychology; the roles of learning, socialization, and culture in evolutionary psychology; and the practical value of applied evolutionary psychology. The article concludes with a discussion of the limitations of current evolutionary psychology.

  9. Prediction of inclusion body solubilization from shaken to stirred reactors.

    PubMed

    Walther, Cornelia; Mayer, Sabrina; Trefilov, Alexandru; Sekot, Gerhard; Hahn, Rainer; Jungbauer, Alois; Dürauer, Astrid

    2014-01-01

    Inclusion bodies (IBs) were solubilized in a µ-scale system using shaking microtiter plates or a stirred tank reactor in a laboratory setting. Characteristic dimensionless numbers for mixing, the Phase number Ph and Reynolds number Re did not correlate with the kinetics and equilibrium of protein solubilization. The solubilization kinetics was independent of the mixing system, stirring or shaking rate, shaking diameter, and energy input. Good agreement was observed between the solubilization kinetics and yield on the µ-scale and laboratory setting. We show that the IB solubilization process is controlled predominantly by pore diffusion. Thus, for the process it is sufficient to keep the IBs homogeneously suspended, and additional power input will not improve the process. The high-throughput system developed on the µ-scale can predict solubilization in stirred reactors up to a factor of 500 and can therefore be used to determine optimal solubilization conditions on laboratory and industrial scale.

  10. Nanoscale magnetic stirring bars for heterogeneous catalysis in microscopic systems.

    PubMed

    Yang, Shuliang; Cao, Changyan; Sun, Yongbin; Huang, Peipei; Wei, Fangfang; Song, Weiguo

    2015-02-23

    Nanometer-sized magnetic stirring bars containing Pd nanoparticles (denoted as Fe3 O4 -NC-PZS-Pd) for heterogeneous catalysis in microscopic system were prepared through a facile two-step process. In the hydrogenation of styrene, Fe3 O4 -NC-PZS-Pd showed an activity similar to that of the commercial Pd/C catalyst, but much better stability. In microscopic catalytic systems, Fe3 O4 -NC-PZS-Pd can effectively stir the reaction solution within microdrops to accelerate mass transfer, and displays far better catalytic activity than the commercial Pd/C for the hydrogenation of methylene blue in an array of microdroplets. These results suggested that the Fe3 O4 -NC-PZS-Pd could be used as nanoscale stirring bars in nanoreactors.

  11. 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.

  12. 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.

  13. 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).

  14. 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

  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. 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).

  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. [On controversies around the Oedipus Complex].

    PubMed

    Drwiega, Marek

    2002-01-01

    In the article the author would like to draw the readers' attention to one of the central issues of psychoanalysis, i.e. Oedipus complex. In the development of the psychoanalysis the classical conception of Oedipus complex presented by Freud gave rise to a severe criticism both on the part of some psychoanalysts, especially women such as e.g. Melanie Klein, and on the part of ethnographers such as B. Malinowski. In the paper the author presents the main controversies concerning this interesting discussion. The fact of the matter is that the Oedipus complex is a hotly debated subject, not only from the cultural point of view but also within the psychoanalytical movement.

  19. Do hormones influence melanoma? Facts and controversies.

    PubMed

    Gupta, Amie; Driscoll, Marcia S

    2010-01-01

    The issue of whether hormones influence malignant melanoma (MM) has been controversial for many years. Although early case reports demonstrated a negative effect of hormones, recent evidence has not supported a potential role for hormones in MM. We address whether exogenous and endogenous hormones influence a woman's risk for MM or affect her prognosis if diagnosed with MM. Multiple epidemiologic studies show the use of oral contraceptives or hormone replacement therapy does not appear to increase a woman's risk for MM. Pregnancy does not appear to influence a woman's risk of MM, nor does pregnancy appear to affect prognosis in the woman diagnosed with MM. When counseling the woman who is diagnosed with MM during pregnancy or during the childbearing years, future use of oral contraceptives or hormone replacement therapy is not contraindicated; counseling concerning future pregnancies should be done on a case-by-case basis, with emphasis placed on established prognostic factors for MM.

  20. 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."

  1. Evolution of the Two Cultures controversy

    NASA Astrophysics Data System (ADS)

    Bieniek, Ronald J.

    1981-05-01

    The Two Cultures schism is a persistent problem in our society. For over a century, scientific spokesmen and literary critics, from T. H. Huxley and M. Arnold to C. P. Snow and F. R. Leavis, have been involved in the Two Cultures issue. This article examines the evolution of the controversy between the ''scientific'' and ''humanistic'' elements of Western culture and its relation to educational policies. The division and antagonism between these two cultures appears to have arisen from differences in the human attitudes that they are preceived to engender. ''Scientific'' professionalism has been associated with a progressive optimism and self-assurance that nurture a broad humanitarianism, while the ''literary'' tradition is characterized by restraint, acceptance, and a more selective humanism.

  2. News and controversies regarding essential tremor.

    PubMed

    Boutin, E; Vaugoyeau, M; Eusebio, A; Azulay, J-P; Witjas, T

    2015-05-01

    Essential tremor is the most common movement disorder in adults. It is characterized by a postural and kinetic tremor affecting the arms, but it can also affect other body parts. It evolves gradually and can be responsible for a functional impairment in activities of daily living. Its pathophysiology remains poorly understood and effective therapeutic options are limited. There are significant semiological variations between patients, and the term "essential tremor" seems to encompass a wide range of heterogeneous clinical phenotypes. The diagnostic criteria presented in 1998 are now challenged. Furthermore, there is a current debate concerning the etiology of this affection, as to whether essential tremor is a complex degenerative disorder or a functional reversible disorder of neuronal oscillation. In this review, we summarize some aspects of clinical, etiologic and therapeutic news, to better address the questioning on unravelling the clinical presentation and examine the current pathophysiological controversy in this disorder.

  3. [Cancer initiating cell theory: popularity and controversies].

    PubMed

    Chen, Hua; Huang, Qiang; Dong, Jun; Lan, Qing

    2006-06-01

    The cancer stem cell model proposes that most tumors are derived from a single cell that is transformed into a cancer-initiating cell (cancer stem cell). Cancer stem cells have the capacity to proliferate, differentiate, and form tumors in vivo. However, the origin of cancer stem cells remains controversial. Normal stem cells are regarded as an ideal candidate for the origin of cancer stem cells when take similar characters and signaling pathways between them into consideration. In addition,cell fusion is an important physiologic process during development and tissue repair,and is closely related to several fundamental features of tumors,and thus could be involved in the development of cancer stem cells.

  4. 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.

  5. Acute Kidney Injury: Diagnostic Approaches and Controversies

    PubMed Central

    Makris, Konstantinos; Spanou, Loukia

    2016-01-01

    Acute kidney injury (AKI) is a significant independent risk factor for morbidity and mortality. In the last ten years a large number of publications have highlighted the limitations of traditional approaches and the inadequacies of conventional biomarkers to diagnose and monitor renal insufficiency in the acute setting. A great effort was directed not only to the discovery and validation of new biomarkers aimed to detect AKI more accurately but also to standardise the definition of AKI. Despite the advances in both areas, biomarkers have not yet entered into routine clinical practice and the definition of this syndrome has many areas of uncertainty. This review will discuss the controversies in diagnosis and the potential of novel biomarkers to improve the definition of the syndrome. PMID:28167845

  6. 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

  7. Controversies in pharmacotherapy of pain management.

    PubMed

    Davis, Mellar P; Walsh, Declan; Lagman, Ruth; LeGrand, Susan B

    2005-09-01

    Since the establishment of the WHO three-step ladder for management of cancer pain, several controversies have arisen, which are partly due to new drug development, reformulations of older analgesics, and technological advancements. As a result, clinicians need clarification of several questions. Is morphine the opioid of choice for moderate to severe pain in cancer? Should combinations of opioids be used? When should spinal opioids be used to treat pain in cancer? What are the appropriate opioid doses for breakthrough pain? Should selective cyclo-oxygenase (COX) 2 inhibitors be used? What is the best tactic to treat neuropathic pain, and what first-line adjuvant analgesic should be used? And do bisphosphonates relieve bone pain in cancers other than breast cancer and myeloma? This review addresses these questions.

  8. The Brugada syndrome: facts and controversies.

    PubMed

    Boussy, Tim; Sarkozy, Andrea; Chierchia, Gian-Battista; Richter, Sergio; Brugada, Pedro

    2007-05-01

    The diagnosis of Brugada syndrome (BS) is based on a combination of clinical (malignant arrhythmias presenting as syncopal or sudden death episodes) and electrocardiographic (pathognomonic ST segment elevation morphology) features. Over the last 15 years, since its introduction as a distinct clinical entity, the BS has been extensively investigated worldwide. In this article an overview of recent developments concerning the genetic background, the diagnostic tools and the therapeutic alternatives will be presented. In the last years, the results of the first medium-term follow-up studies have also been published. Some of these studies present contradictory results, especially concerning the identification of useful sudden death predictors in asymptomatic patients. The review presented here will discuss this prognostic controversy and will offer possible explanations for the different results.

  9. Status Report: Black Hole Complementarity Controversy

    NASA Astrophysics Data System (ADS)

    Lee, Bum-Hoon; Yeom, Dong-han

    2014-01-01

    Black hole complementarity was a consensus among string theorists for the interpretation of the information loss problem. However, recently some authors find inconsistency of black hole complementarity: large N rescaling and Almheiri, Marolf, Polchinski and Sully (AMPS) argument. According to AMPS, the horizon should be a firewall so that one cannot penetrate there for consistency. There are some controversial discussions on the firewall. Apart from these papers, the authors suggest an assertion using a semi-regular black hole model and we conclude that the firewall, if it exists, should affect to asymptotic observer. In addition, if any opinion does not consider the duplication experiment and the large N rescaling, then the argument is difficult to accept.

  10. 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.

  11. 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.

  12. 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.

  13. Generation of Protein Crystals Using a Solution-Stirring Technique

    NASA Astrophysics Data System (ADS)

    Adachi, Hiroaki; Niino, Ai; Matsumura, Hiroyoshi; Takano, Kazufumi; Kinoshita, Takayoshi; Warizaya, Masaichi; Inoue, Tsuyoshi; Mori, Yusuke; Sasaki, Takatomo

    2004-06-01

    Crystals of bovine adenosine deaminase (ADA) were grown over a two week period in the presence of an inhibitor, whereas ADA crystals did not form using conventional crystallization methods when the inhibitor was excluded. To obtain ADA crystals in the absence of the inhibitor, a solution-stirring technique was used. The crystals obtained using this technique were found to be of high quality and were shown to have high structural resolution for X-ray diffraction analysis. The results of this study indicate that the stirring technique is a useful method for obtaining crystals of proteins that do not crystallize using conventional techniques.

  14. 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.

  15. 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.

  16. Six controversial issues on subclinical Cushing's syndrome.

    PubMed

    Chiodini, Iacopo; Albani, Adriana; Ambrogio, Alberto Giacinto; Campo, Michela; De Martino, Maria Cristina; Marcelli, Giorgia; Morelli, Valentina; Zampetti, Benedetta; Colao, Annamaria; Pivonello, Rosario

    2016-07-12

    Subclinical Cushing's syndrome is a condition of hypercortisolism in the absence of signs specific of overt cortisol excess, and it is associated with an increased risk of diabetes, hypertension, fragility fractures, cardiovascular events and mortality. The subclinical Cushing's syndrome is not rare, being estimated to be between 0.2-2 % in the adult population. Despite the huge number of studies that have been published in the recent years, several issues remain controversial for the subclinical Cushing's syndrome screening, diagnosis and treatment. The Altogether to Beat Cushing's syndrome Group was founded in 2012 for bringing together the leading Italian experts in the hypercortisolism-related diseases. This document represents the Altogether to Beat Cushing's syndrome viewpoint regarding the following controversial issues on Subclinical Cushing's syndrome (SCS): (1) Who has to be screened for subclinical Cushing's syndrome? (2) How to screen the populations at risk? (3) How to diagnose subclinical Cushing's syndrome in patients with an adrenal incidentaloma? (4) Which consequence of subclinical Cushing's syndrome has to be searched for? (5) How to address the therapy of choice in AI patients with subclinical Cushing's syndrome? (6) How to follow-up adrenal incidentaloma patients with subclinical Cushing's syndrome surgically or conservatively treated? Notwithstanding the fact that most studies that faced these points may have several biases (e.g., retrospective design, small sample size, different criteria for the subclinical Cushing's syndrome diagnosis), we believe that the literature evidence is sufficient to affirm that the subclinical Cushing's syndrome condition is not harmless and that the currently available diagnostic tools are reliable for identifying the majority of individuals with subclinical Cushing's syndrome.

  17. Manufacturing Systems Demonstration: Bimetallic Friction STIR Joining of AA6061 and High Hardness Steel

    DTIC Science & Technology

    2013-05-31

    DESCRIPTION OF FRICTION STIR PROCESSES ................................................... 2 D. DEVELOPMENT OF BIMETALLIC ( ALUMINUM - STEEL ) FRICTION STIR...to successfully join AA6061 aluminum alloy and High Hardness Armor (HHA) steel using the friction stir process (FSP). Metallographic analysis...32262: Detail Specification, Armor Plate Aluminum Alloy, Unweldable Applique 6061 2 MIL-DTL-46100E: Armor Plate, Steel , Wrought, High-Hardness

  18. 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.

  19. 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.

  20. 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…

  1. 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.

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

    DTIC Science & Technology

    2013-08-01

    and around particle inclusions within the WZ. In the case of FSW aluminum to steel , the structure often seen is one of steel particles dispersed...the microstructure and mechanical performance of dissimilar FSWs between aluminum and steel , this study focuses on the characterization of the...MICROSTRUCTURAL CHARACTERIZATION OF FRICTION STIR WELDED ALUMINUM - STEEL JOINTS By ERIN ELIZABETH PATTERSON A thesis submitted in

  3. 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.

  4. Nano-Sized Grain Refinement Using Friction Stir Processing

    DTIC Science & Technology

    2013-03-01

    state process developed on the basis of the friction stir welding ( FSW ) technique invented by The Welding Institute (TWI) in 1991 [2]. During FSP...nitrogen cooling. Tool Geometry Effects on Heat Input During FSP During FSW or FSP, peak temperature in the nugget zone plays a vital role in

  5. 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.

  6. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Santella, M. L.; Hovanski, Yuri; Grant, Glenn J.; Carpenter, Joseph A.; Warren, C. D.; Smith, Mark T.

    2008-12-28

    Experiments are continuing to evaluate the feasibility of friction stir spot welding advanced high-strength steels including, DP780, martensitic hot-stamp boron steel, and TRIP steels. Spot weld lap-shear strengths can exceed those required by industry standards such as AWS D8.1.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Child injury control: trends, themes, and controversies.

    PubMed

    Johnston, Brian D; Ebel, Beth E

    2013-01-01

    Injury is a major cause of morbidity and mortality among US children, and an important driver of health status globally. Despite its enormous burden, injury is preventable. Over the last 10 years, significant progress has been made in the reduction of unintentional injury among US children. However, aggregate trends mask important disparities by age group, region, and injury mechanism. Basic and translation research is needed to develop and test prevention strategies to address these new or recalcitrant problems. Motor vehicle occupant injury has fallen to historic lows, but challenges remain in protecting novice drivers and managing the distraction of new technologies. Injury to pedestrians has also declined, but likely as a result of decreased exposure as fewer children walk. This calls for a broader public health perspective to promote activity while enhancing safety. Deaths due to drowning are common and illustrate the difficulty in measuring and promoting appropriate supervision. Environmental modification and use of protective products may be a more appropriate response. Concussion in sport is another challenging issue: public health laws promote identification and appropriate management of concussed athletes, but less progress has been made on primary prevention of these injuries. Unintentional poisoning is on the rise, attributable to misuse of, and overdose with, prescription opioids. Injury deaths to infants are also increasing. This trend is driven in part by better death investigation that classifies more sleep-related deaths as suffocation events. Finally, we examine a sample of cross-cutting themes and controversies in injury control that might be amenable to empiric evaluation.

  13. IL-1: discoveries, controversies and future directions.

    PubMed

    Dinarello, Charles A

    2010-03-01

    Although there has been a great amount of progress in the 25 years since the first reporting of the cDNA for IL-1alpha and IL-1beta, the history of IL-1 goes back to the early 1940s. In fact, the entire field of inflammatory cytokines, TLR and the innate immune response can be found in the story of IL-1. This Viewpoint follows the steps from the identification of the fever-inducing activities of "soluble factors" produced by endotoxin-stimulated leukocytes through to the discovery of cryopyrin and the caspase-1 inflammasome and on to the clinical benefits of anti-IL-1beta-based therapeutics. It also discusses some of the current controversies regarding the activation of the inflammasome. The future of novel anti-inflammatory agents to combat chronic inflammation is based, in part, on the diseases that are uniquely responsive to anti-IL-1beta, which is surely a reason to celebrate the 25th anniversary of the cloning of IL-1alpha and IL-1beta.

  14. Discoveries and controversies in cutaneous mosaicism.

    PubMed

    Castori, Marco; Tadini, Gianluca

    2016-06-01

    Genetic mosaicism is thought to be a common phenomenon in inherited skin disorders. It is the leading molecular mechanism explaining cutaneous hamartomas and nevoid disorders, skin manifestations of most X-linked genodermatoses and specific forms of clinical variability and topographic distribution in autosomal skin disorders. The developmental (in utero) origin and timing dependence are two major attributes for the current definition of cutaneous mosaicism. Chromosomal mosaicism, lyonization in X-linked genodermatoses, and various types of mosaicism (i.e. type 1, type 2 and revertant mosaicism) in autosomal skin disorders are mechanisms well defined at the molecular level. All these concepts have been fully included in the current medical terminology in dermatology and genetics. Mitotic crossing-over, paradominant inheritance, monoallelic expression of autosomal traits and mosaicism in acquired skin disorders remain without a formal molecular proof and still represent sources of debate in the scientific community. This review summarizes current concepts, discoveries and controversies in the field of cutaneous mosaicism for practitioners and clinical researchers to enhance their understanding of such a underestimated clinical phenomenon and its biological basis.

  15. [Giant viruses: update, enigmas, controversies and perspectives].

    PubMed

    Claverie, Jean-Michel; Abergel, Chantal

    2016-12-01

    Unlike microbes known in his time, the first virus (that of tobacco mosaic disease) was discovered by Ivanoski in 1892 because it was not retained by Chamberland's porcelain candles. For more than a century afterward, viruses were equated with this simple property that is still extensively used today (using modern 0,2 µm pore filters) as a practical criterion to delineate the "viral fraction" from other microbes in medical or environmental samples. The first documented exception to the simplistic criterion of particle size came with the discovery of Mimivirus, the viral nature of which was eventually recognized in 2003, following ten years during which it was mistaken for an obligate intracellular bacterium. Thirteen more years later, we now realize that non-filtering "giant viruses" are not rare, probably ubiquitous, and come in a large variety of virion shapes, genome sizes, gene contents, and replication strategies. Following a quick description of the 4 giant virus families known today, we discuss the enigmas, controversies and perspectives of conceptual revolutions that are brought about by this new and booming area of virology.

  16. Mendelian controversies: a botanical and historical review.

    PubMed

    Fairbanks, D J; Rytting, B

    2001-05-01

    Gregor Mendel was a 19(th) century priest and botanist who developed the fundamental laws of inheritance. The year 2000 marked a century since the rediscovery of those laws and the beginning of genetics. Although Mendel is now recognized as the founder of genetics, significant controversy ensued about his work throughout the 20(th) century. In this paper, we review five of the most contentious issues by looking at the historical record through the lens of current botanical science: (1) Are Mendel's data too good to be true? (2) Is Mendel's description of his experiments fictitious? (3) Did Mendel articulate the laws of inheritance attributed to him? (4) Did Mendel detect but not mention linkage? (5) Did Mendel support or oppose Darwin?A synthesis of botanical and historical evidence supports our conclusions: Mendel did not fabricate his data, his description of his experiments is literal, he articulated the laws of inheritance attributed to him insofar as was possible given the information he had, he did not detect linkage, and he neither strongly supported nor opposed Darwin.

  17. The catatonia conundrum: controversies and contradictions.

    PubMed

    Padhy, Susanta Kumar; Parakh, Preeti; Sridhar, M

    2014-02-01

    Although catatonia is known to psychiatrists for more than a century, it is still poorly understood, often under recognized, have inspired debate and criticism about nosological status of the catatonic syndrome in recent times without reaching its conclusion. It can present with a number of psychiatric and medical illnesses and is easily treatable, though treatment response varies depending upon the underlying condition and can lead on to a multitude of complications, if not treated. Some issues are more than forty catatonic signs are available to scientific audience for diagnosis; threshold number for labelling varies according to the nosological system followed and the underlying condition; and mood stabilizers like carbamazepine and lithium are helpful in some cases of idiopathic periodic catatonia. Researchers have been asking for a separate diagnostic category for catatonia since long and the debate has gained pace over the last few years, with new editions of both DSM and ICD coming up. Therefore, this paper looks at the controversies associated with the diagnosis and classification of catatonia, the arguments and counter-arguments and future directions, in crisp.

  18. 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.

  19. Iron hypothesis of cardiovascular disease: still controversial.

    PubMed

    Aursulesei, Viviana; Cozma, A; Krasniqi, A

    2014-01-01

    Iron hypothesis has been a controversial subject for over 30 years as many studies support its role as a risk factor for cardiovascular disease, while other studies found no evidence to support it. The conflicting results are accounted for by the non-homogeneity of trial design in terms of population inclusion criteria and different endpoints, non-uniform use of parameters for assessing iron role, and incomplete understanding of the mechanisms of action. The nature of iron is dual, being of crucial importance for the human body, but also toxic as "free iron" induces oxidative stress. Under physiological conditions, there are efficient and complex mechanisms against iron-induced oxidative stress, which could be reproduced for creating new, intelligent antioxidants. Iron depletion improves the cardiovascular prognosis only if serum concentration is at the lowest limit of normal ranges. However, low iron levels and the type of dietary iron intake correlate with atherosclerotic cardiovascular disease, influence the ischemic endpoints in the elderly, and exert negative impact on heart failure prognosis. So far, the causal relation and involved mechanisms are not fully elucidated. Iron overload is a difficult and frequent condition, involving the cardiovascular system by specific pathogenic pathways, therefore determining a particular form of restrictive cardiomyopathy and vaso-occlusive arterial damage.

  20. Aortic arch dissection: a controversy of classification.

    PubMed

    Lempel, Jason K; Frazier, Aletta Ann; Jeudy, Jean; Kligerman, Seth J; Schultz, Randall; Ninalowo, Hammed A; Gozansky, Elliott K; Griffith, Bartley; White, Charles S

    2014-06-01

    Aortic dissections originating in the ascending aorta and descending aorta have been classified as type A and type B dissections, respectively. However, dissections with intimal flap extension into the aortic arch between the innominate and left subclavian arteries are not accounted for adequately in the widely used Stanford classification. This gap has been the subject of controversy in the medical and surgical literature, and there is a tendency among many radiologists to categorize such arch dissections as type A lesions, thus making them an indication for surgery. However, the radiologic perspective is not supported by either standard dissection classification or current clinical management. In this special report, the origin of dissection classification and its evolution into current radiologic interpretation and surgical practice are reviewed. The cause for the widespread misconception about classification and treatment algorithms is identified. Institutional review board approval and waiver of informed consent were obtained as part of this HIPAA-compliant retrospective study to assess all aortic dissection studies performed at the University of Maryland Medical Center, Baltimore between 2010 and 2012 to determine the prevalence of arch dissections. Finally, a unified classification system that reconciles imaging interpretation and management implementation is proposed.

  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. Lyme disease: diagnostic issues and controversies.

    PubMed

    Aguero-Rosenfeld, Maria E; Wormser, Gary P

    2015-01-01

    The diagnosis of Lyme disease is a controversial topic. Most practitioners and scientists recognize that Lyme disease is associated with certain objective clinical manifestations supported by laboratory evidence of infection with Borrelia burgdorferi sensu lato (the etiologic agent). There are others, however, who believe that patients with Lyme disease may have a wide variety of entirely nonspecific symptoms without any objective clinical manifestation and that laboratory evidence of infection by B. burgdorferi is not required to support the diagnosis. In reality, this perspective is not evidence based and would inevitably lead to innumerable misdiagnoses, given the high frequency of medically unexplained symptoms, such as fatigue and musculoskeletal pains, in the general population. Although those espousing this viewpoint do not believe that a positive laboratory test is required, nevertheless, they often seek out and promote alternative, unapproved testing methods that frequently provide false-positive results to justify their diagnosis. Herein, we provide a brief overview of Lyme disease testing, emphasizing current usage and limitations. We also discuss the use of nonvalidated procedures and the prospects for a reduction in such testing practices in the future.

  3. Controversies in the management of pancreatic IPMN.

    PubMed

    Tanaka, Masao

    2011-01-01

    Although considerable progress has been made in our understanding of intraductal papillary mucinous neoplasm (IPMN) of the pancreas, some issues still remain to be resolved. Uncertainty exists regarding the classification of IPMNs. The necessity of the mixed-type category of IPMN and whether such lesions should be defined radiographically or histologically needs to be determined. The preoperative distinction of branch duct IPMNs from nonmucinous cysts should be further investigated so that potentially malignant lesions can be identified and management strategies guided effectively. The role and safety of cystic fluid analysis remains to be clarified in this context. With regard to the diagnosis of malignancy in branch duct IPMNs, criteria for identifying malignancy need to be re-evaluated. The presence of mural nodules is a very reliable predictor; however, controversy exists over the value of size as a reliable indicator. Criteria with increased specificity are needed, perhaps including histological subtype of lesion, to reduce the false-positive rate of the present criteria. Finally, the best modality and interval for surveillance of branch duct IPMNs requires determination because of its significance in terms of malignant transformation, development of distinct ductal adenocarcinoma and disease recurrence after resection.

  4. Polyp Resection - Controversial Practices and Unanswered Questions.

    PubMed

    von Renteln, Daniel; Pohl, Heiko

    2017-03-09

    Detection and complete removal of precancerous neoplastic polyps are central to effective colorectal cancer screening. The prevalence of neoplastic polyps in the screening population in the United States is likely >50%. However, most persons with neoplastic polyps are never destined to develop cancer, and do not benefit for finding and removing polyps, and may only be harmed by the procedure. Further 70-80% of polyps are diminutive (≤5 mm) and such polyps almost never contain cancer. Given the questionable benefit, the high-cost and the potential risk changing our approach to the management of diminutive polyps is currently debated. Deemphasizing diminutive polyps and shifting our efforts to detection and complete removal of larger and higher-risk polyps deserves discussion and study. This article explores three controversies, and emerging concepts related to endoscopic polyp resection. First, we discuss challenges of optical resect-and-discard strategy and possible alternatives. Second, we review recent studies that support the use of cold snare resection for ≥5 mm polyps. Thirdly, we examine current evidence for prophylactic clipping after resection of large polyps.

  5. 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

  6. 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

  7. 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

  8. Controversies in Treatment of Acetabular Fracture

    PubMed Central

    Grubor, Predrag; Krupic, Ferid; Biscevic, Mirza; Grubor, Milan

    2015-01-01

    Introduction: Acetabular fractures treatment represents a great controversy, challenge and dilemma for an orthopedic surgeon. Aim: The aim of the paper was to present the results of treatment of 96 acetabular fractures in the Clinic of Traumatology Banja Luka, in the period from 2003 to 2013, as well as to raise awareness regarding the controversy in the methods of choice in treating acetabulum fractures. Material and methods: The series consists of 96 patients, 82 males and 14 females, average age 40.5 years. Traffic trauma was the cause of fractures in 79 patients (85%), and in 17 patients (15%) fractures occurred due to falls from height. Polytrauma was present in 31 patients (32%). According to the classification of Judet and Letournel, representation of acetabular fractures was as follows: posterior wall in 32 patients, posterior column in 28, anterior wall in 4, anterior column in 2, transverse fractures in 8, posterior wall and posterior column in 10, anterior and posterior wall in 6, both- column in 4 and transversal fracture and posterior wall in 2 patients. 14 patients were treated with traction, that is, 6 patients with femoral traction and 8 patients with both lateral and femoral traction. 82 patients (86.4%) were surgically treated. Kocher-Langenbeck approach was applied in the treatment of 78 patients. In two patients from the Kocher-Langenbeck’s approach, the Ollier’s approach had to be applied as well. Two acetabular were primarily treated with Ollier’s approach. Extended Smith- Peterson’s approach was applied 4 times, and Emile Letournel’s (ilioinguinal) approach 14 times. Results: Functional outcome (after follow-up of 18 months), according to the Harris hip score of surgical treatment in 82 patients, was as follows: good 46 (56%), satisfactory 32 (39%) and poor 4 (5%). Results of acetabulum fractures treated with traction were: good 8 (57%), satisfactory 4 (28%) and poor 2 (15%). According to the Brook’s classification of heterotopic

  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

    2015-10-06

    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.

  10. Psychological controversies in gastroparesis: A systematic review

    PubMed Central

    Woodhouse, Sally; Hebbard, Geoff; Knowles, Simon R

    2017-01-01

    AIM To systematically review literature addressing three key psychologically-oriented controversies associated with gastroparesis. METHODS A comprehensive search of PubMed, CINAHL, and PsycINFO databases was performed to identify literature addressing the relationship between gastroparesis and psychological factors. Two researchers independently screened all references. Inclusion criteria were: an adult sample of gastroparesis patients, a quantitative methodology, and at least one of the following: (1) evaluation of the prevalence of psychopathology; (2) an outcome measure of anxiety, depression, or quality of life; and (3) evidence of a psychological intervention. Case studies, review articles, and publications in languages other than English were excluded from the current review. RESULTS Prevalence of psychopathology was evaluated by three studies (n = 378), which found that combined anxiety/depression was present in 24% of the gastroparesis cohort, severe anxiety in 12.4%, depression in 21.8%-23%, and somatization in 50%. Level of anxiety and depression was included as an outcome measure in six studies (n = 1408), and while limited research made it difficult to determine the level of anxiety and depression in the cohort, a clear positive relationship with gastroparesis symptom severity was evident. Quality of life was included as an outcome measure in 11 studies (n = 2076), with gastroparesis patients reporting lower quality of life than population norms, and a negative relationship between quality of life and symptom severity. One study assessed the use of a psychological intervention for gastroparesis patients (n = 120) and found that depression and gastric function were improved in patients who received psychological intervention, however the study had considerable methodological limitations. CONCLUSION Gastroparesis is associated with significant psychological distress and poor quality of life. Recommendations for future studies and the development of

  11. Carotid endarterectomy: current consensus and controversies.

    PubMed

    Meerwaldt, Robbert; Hermus, Linda; Reijnen, Michel M P J; Zeebregts, Clark J

    2010-10-01

    Stroke is the third most common cause of mortality, and carotid artery stenosis causes 8% to 29% of all ischemic strokes. Best medical treatment forms the basis of carotid stenosis treatment, and carotid endarterectomy (CEA) has an additional beneficial effect in high-grade stenosis. Carotid angioplasty and stenting (CAS) has challenged CEA as a primary carotid intervention. At present, CEA remains the gold standard, but in the future, CAS techniques will evolve and might become beneficial for subgroups of patients with carotid stenosis. This chapter briefly describes the history of carotid interventions and current consensus and controversies in CEA. In the last two years, several meta-analyses were published on a variety of aspects of best medical treatment, CEA, and CAS. It is still a matter of debate as to whether asymptomatic patients with carotid stenosis should undergo a carotid intervention. Especially because medical treatment has dramatically evolved since the early carotid trials. On the other hand, it is clear that carotid interventions in symptomatic patients with a high-grade stenosis should be performed as early as possible after the initial neurological event in order to achieve optimal stroke risk reduction. In CEA, the use of patching is advocated above primary closure, while the role of selective patching is still unclear. No differences in stroke and mortality rates are observed for routine versus selective shunting, for conventional versus eversion CEA, or for local versus general anesthesia. It is anticipated that in the future, there will be several interesting developments in carotid interventions such as plaque morphology analysis, acute interventions during stroke in progress, and further evolvement of CAS techniques.

  12. Controversy erupts in Brazil over penis nicknames.

    PubMed

    1995-10-09

    Commissioned by the Brazilian health ministry to conduct a publicity campaign designed to encourage the use of condoms, the Master Communication and Marketing company conducted a survey in which it collected dozens of nicknames for the penis. The television component of the campaign involves an actor who holds a heart-to-heart conversation with his penis, recommending that it use condoms and showing it, with a candle, how to do so. "Braulio" was chosen as the name for the penis. Braulio, however, is a common men's name in Brazil. Shortly after the launch of the campaign, men named Braulio staged numerous protests against the use of their name. The Health Minister subsequently suspended the campaign on September 23, 1995, to allow selection of an alternate name for the penis. The campaign has resumed, this time using eight impersonal expressions such as "partner" and "him" to identify the penis, and is planned to run for three months despite the controversy. A journalist formerly named Braulio has officially changed his name to avoid being mocked, a lawyer in Sao Paulo named Braulio will continue to head a suit against the government filed by a group of Braulios alleging moral damage, and the Catholic Church criticizes the bluntness of the campaign, which mentions oral and anal sex on the radio. Nonetheless, a health ministry poll of almost 1000 people found that 80% supported the campaign. The coordinator of the Program of Sexually Transmitted Diseases insists that the blunt language is necessary to reach the lower-income, less-educated masculine population. Official figures indicate that 80% of the slightly more than 71,000 registered AIDS cases in Brazil are among men aged 19-35 years, and it is among men aged 20-40 years that HIV is spreading most rapidly. The health ministry has been bombarded with alternate nicknames for the penis since the initial uproar, enough to fill a book. The article points out that the nicknames vary according to region.

  13. 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

  14. 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.

  15. Lichen Planus Pigmentosus: The Controversial Consensus.

    PubMed

    Ghosh, Aparajita; Coondoo, Arijit

    2016-01-01

    A pigmented variant of lichen planus (LP) was first reported from India in 1974 by Bhutani et al. who coined the term LP pigmentosus (LPP) to give a descriptive nomenclature to it. LP has a number of variants, one of which is LPP. This disease has also later been reported from the Middle East, Latin America, Korea, and Japan, especially in people with darker skin. It has an insidious onset. Initially, small, black or brown macules appear on sun-exposed areas. They later merge to form large hyperpigmented patches. The disease principally affects the sun-exposed areas of the body such as the face, trunk, and upper extremities. The oral mucosa may rarely be involved. However, the palms, soles, and nails are not affected. Histologically, the epidermis is atrophic along with vacuolar degeneration of basal cell layer. The dermis exhibits incontinence of pigment with scattered melanophages and a sparse follicular or perivascular infiltrate. There is a considerable similarity in histopathological findings between LPP and erythema dyschromicum perstans. However, there are immunologic and clinical differences between the two. These observations have led to a controversy regarding the identity of the two entities. While some dermatologists consider them to be the same, others have opined that the two should be considered as distinctly different diseases. A number of associations such as hepatitis C virus infection, frontal fibrosing alopecia, acrokeratosis of Bazex and nephrotic syndrome have been reported with LPP. A rare variant, LPP inversus, with similar clinical and histopathological findings was reported in 2001. As opposed to LPP, this variant occurs in covered intertriginous locations such as groins and axillae and mostly affects white-skinned persons.

  16. Lichen Planus Pigmentosus: The Controversial Consensus

    PubMed Central

    Ghosh, Aparajita; Coondoo, Arijit

    2016-01-01

    A pigmented variant of lichen planus (LP) was first reported from India in 1974 by Bhutani et al. who coined the term LP pigmentosus (LPP) to give a descriptive nomenclature to it. LP has a number of variants, one of which is LPP. This disease has also later been reported from the Middle East, Latin America, Korea, and Japan, especially in people with darker skin. It has an insidious onset. Initially, small, black or brown macules appear on sun-exposed areas. They later merge to form large hyperpigmented patches. The disease principally affects the sun-exposed areas of the body such as the face, trunk, and upper extremities. The oral mucosa may rarely be involved. However, the palms, soles, and nails are not affected. Histologically, the epidermis is atrophic along with vacuolar degeneration of basal cell layer. The dermis exhibits incontinence of pigment with scattered melanophages and a sparse follicular or perivascular infiltrate. There is a considerable similarity in histopathological findings between LPP and erythema dyschromicum perstans. However, there are immunologic and clinical differences between the two. These observations have led to a controversy regarding the identity of the two entities. While some dermatologists consider them to be the same, others have opined that the two should be considered as distinctly different diseases. A number of associations such as hepatitis C virus infection, frontal fibrosing alopecia, acrokeratosis of Bazex and nephrotic syndrome have been reported with LPP. A rare variant, LPP inversus, with similar clinical and histopathological findings was reported in 2001. As opposed to LPP, this variant occurs in covered intertriginous locations such as groins and axillae and mostly affects white-skinned persons. PMID:27688435

  17. 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…

  18. 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…

  19. 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…

  20. 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…

  1. 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).…

  2. 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,"…

  3. Integrating Art Education Models: Contemporary Controversies in Spain

    ERIC Educational Resources Information Center

    Belver, Manuel; Ulln, Ana; Acaso, Mara

    2005-01-01

    In this article, a basic controversy for art education in Spain is analysed, and its antecedents in thought and social and artistic practices are reviewed. The controversy refers to the question whether school art education should be oriented towards the fine arts or towards the manual arts. Consequently, which should be the cultural model of…

  4. 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…

  5. 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…

  6. 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…

  7. 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…

  8. 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…

  9. 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…

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

    PubMed

    Marres, Noortje

    2015-09-01

    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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. A stirred bath technique for diffusivity measurements in cell matrices.

    PubMed

    Chresand, T J; Dale, B E; Hanson, S L; Gillies, R J

    1988-10-05

    A stirred bath technique was developed for determining effective diffusivities in cell matrices. The technique involves cell immobilization in a dilute gel which has negligible effect on solute diffusion. Agar and collagen were tested as immobilizing gels. Agar gel was shown to have minor interactions with the diffusion of various biological molecules, and was used for immobilization of Ehrlich Ascites Tumor (EAT) cells. Diffusivities of glucose and lactic acid were measured in EAT matrices for cell loadings between 20 and 45 vol %. Treatment with glutaraldehyde was effective in quenching the metabolic activity of the cells while preserving their physical properties and diffusive resistance. The measured data agree favorably with predictions based on Maxwell's equation for effective diffusion in a periodic composite material. The stirred bath technique is useful for diffusivity determinations in immobilized matrices or free slurries, and is applicable to both microbial and mammalian cell systems.

  16. 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).

  17. 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.

  18. 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.

  19. Predicting the forming limit of friction stir welded blanks

    NASA Astrophysics Data System (ADS)

    Ramulu, Perumalla Janaki; Narayanan, R. Ganesh

    2011-05-01

    Friction stir welded blanks (FSWB) are tailored blanks made by friction stir welding of sheets of different thicknesses and quality. In order to reduce the trial-and-error principles and costs, the computational simulation of stamping processes of FSW blanks is required for which a feasible methodology or theory to evaluate the forming characteristics has to be incorporated. In the present work, the validity of effective strain rate based necking criterion (ESRC) in both original and modified forms to predict the forming limit of FSW blanks made of AA6111, DP590 is analyzed. The FLC thus predicted is compared with FLC from thickness gradient based necking criterion and from literature. It is found from the validation done with literature results that a consistent and accurate forming limit prediction is obtained from modified ESRC when compared to original ESRC. The failure pattern prediction is also agreeing well with the literature results.

  20. Path Force Control for Friction Stir Welding Processes (Preprint)

    DTIC Science & Technology

    2009-02-01

    maintained, even in the presence of gaps, and wormhole generation during the welding process is eliminated by regulating the path force. 15. SUBJECT... wormhole generation during the welding process is eliminated by regulating the path force. INTRODUCTION Friction Stir Welding (FSW) is a new solid...the force in the direction of tool motion) is regulated. It will be seen that wormholes can be eliminated by regulating the path force

  1. Meeting Report: From Stirring to Mixing in a Stratified Ocean

    DTIC Science & Technology

    2001-01-19

    ocean circulation models , J. Phys. Oceanogr., 20, 150-155, 1990. Jim~nez, J., Turbulence . In Developments in Fluid Mechanics, ed. G.K. Batchelor, K...scalar is stirred and mixed in a scalar is related by a tensor to the local gradient of the turbulent flow (Eckart, 1948). At first, during the...dynami- system using the potential density instead. cal systems theory, (3) inertial instability, submesoscale These results are purely kinematic

  2. Feasibility of Underwater Friction Stir Welding of HY-80 Steel

    DTIC Science & Technology

    2011-03-01

    FSW ) of high-strength; quench and temper low carbon steels that are susceptible to hydrogen-assisted cracking (HAC). The specific benefits of...is to determine the feasibility of underwater friction stir welding ( FSW ) of high-strength, quench and temper low carbon steels that are...Tungsten-Rhenium binder was used to conduct three bead-on-plate FSW traverses, approximately 40 inches in length on 0.25 inch HY-80 steel . The

  3. Feasibility of Underwater Friction Stir Welding of Hardenable Alloy Steel

    DTIC Science & Technology

    2010-12-01

    bead-on-plate FSW traverses, approximately 64 inches (1.6 m) in total length, on 0.25 inch (6.4 mm) thick plates of a hardenable alloy steel . The...base plate. Based on preliminary findings, FSW of hardenable alloy steel is a feasible process and should be further researched and refined. 15...v ABSTRACT The objective of this thesis is to determine whether friction stir welding ( FSW ) is a feasible welding process for steels in an

  4. 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.

  5. 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.

  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, 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.

  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, 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.

  9. 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).

  10. On the potentialities of intensification of electromagnetic stirring of melts

    NASA Astrophysics Data System (ADS)

    Branover, H.; Golbraikh, E.; Kapusta, A.; Mikhailovich, B.; Dardik, I.; Thompson, R.; Lesin, S.; Khavkin, M.

    2006-09-01

    The effciency of technological processes of producing metals and alloys, continuous ingots and castings of ferrous and non­ferrous metals is mainly determined by the intensity of heat and mass transfer in the liquid phase. To increase the latter, various methods are used, including electromagnetic ones. Most electromagnetic methods are based on the application of electromagnetic fields, harmonically varying in time. In this case, the mean velocity of metal motion is a determining parameter. Since the process of stirring is directly connected with the turbulence level in the flow, the latter is also determined by the mean velocity value. In the present paper, we set forth the results of the studies of liquid metal flows in anharmonic rotating magnetic fields generated by amplitude­modulated alter­ native currents in inductor coils. As demonstrated below, changes in modulation parameters lead to the appearance of additional degrees of freedom in the control of turbulent flows of liquid metals and expand the potentialities for controlling the processes of stirring. With a suitable choice of the modulation parameters, we can considerably increase the intensity of melt stirring at the expense of increased turbulent transfer intensity due to the excitation of the so­called forced turbulence, without increasing the mean velocity of convective flows. Thus, in this case, a more intense mixing can be achieved due to a more intense turbulent transfer at a reduced mean velocity (convective transfer). Figs 4, Refs 4.

  11. Telehomecare technology across sectors: claims of jurisdiction and emerging controversies

    PubMed Central

    Dinesen, Birthe; Gustafsson, Jeppe; Nøhr, Christian; KjærAndersen, Stig; Sejersen, Holger; Toft, Egon

    2007-01-01

    Purpose The purpose of this study was to explore and identify inter-organisational and inter-professional controversies that emerge when telehomecare technology is implemented across healthcare sectors. Theory A combined inter-organisational and inter-professional perspective constitutes the conceptual framework for this study. Methods The case study approach was applied as the overall methodology of the study. A triangulation of data collection techniques was used in order to provide multiple sources of evidence for exploring and identifying controversies (documents, participant observation, qualitative interviews, focus group interviews). Findings During the design and implementation phases of a telehomecare system, several types of controversies emerged as part of the inter-organisational and inter-professional agenda. These controversies involved competing claims of jurisdiction, controversies over knowledge technologies, or differences in network visions and network architecture. Discussion and conclusions The identification of such controversies and differences in the design and implementation process of the concept of home hospitalisation for heart patients by means of telehomecare technology can contribute to the uncovering of new knowledge. These issues should be taken into account when initiating a telehomecare project and implementing telehomecare technology. Technology in a network and across inter-professional relations poses a challenge to this new field. There is a particular need to precisely define the claims of jurisdiction, and the accompanying controversies that can arise related to knowledge technologies, network visions and network architecture. PMID:18043726

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. Some properties of a stir-cast Ni-Cr based dental alloy.

    PubMed

    Boswell, P G; Stevens, L

    1980-06-01

    A Ni-Cr based crown and bridge alloy has been successfully stir-cast into small investment mould spaces using a modified induction melting and casting machine. Stir-casting produced substantial improvements to the mechanical properties of the cast alloy. A model for the development of the stir-cast microstructure is described and the clinical significance of the improvements in the alloy's properties is discussed.

  17. State of the art: therapeutic controversies in severe acute asthma.

    PubMed

    Gibbs, M A; Camargo, C A; Rowe, B H; Silverman, R A

    2000-07-01

    This is a transcript of the 1999 SAEM State-of-the-Art session on "Therapeutic Controversies in Severe Acute Asthma," presented at the 1999 SAEM annual meeting in Boston. The aim of this session was to address some of the current controversies in the management of acute asthma exacerbations, a major issue in emergency medicine. Despite many recent advances in asthma management, morbidity and mortality remain high. While many of us have strong feelings on how asthma patients should be treated, many of our assertions are not based on good science, and there are numerous areas of controversy. This discussion focuses on the controversy over beta agonist treatment for acute asthma, the physiology of corticosteroids in asthma, and the emergency use of leukotriene-modifying agents.

  18. 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.

  19. 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)

  20. 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...

  1. 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)

  2. 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

  3. Controversy of the year. Biomedical ethics on the front burner.

    PubMed

    2000-12-22

    CONTROVERSY OF THE YEAR: Biomedical Ethics on the Front Burner It was a hot year for debates over research ethics. Controversy erupted in late 1999 after the death of 18-year-old Jesse Gelsinger in a gene-therapy clinical trial at the University of Pennsylvania. Because Penn and one of its clinicians had a financial stake in a gene-therapy company, questions about potential conflicts of interest arose at once.

  4. 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

  5. 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.

  6. 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).

  7. Oxide Evolution in ODS Steel Resulting From Friction Stir Welding

    DTIC Science & Technology

    2014-06-01

    Master’s Thesis 4 . TITLE AND SUBTITLE OXIDE EVOLUTION IN ODS STEEL RESULTING FROM FRICTION STIR WELDING 5. FUNDING NUMBERS 6 . AUTHOR(S...temperatures, from [5]. ........... 6   Figure 4 .  The phase diagram for aluminum and yttrium oxide, from [13]. ......................8  Figure 5...millimeters per minute. FSW Conditions RPM IPM MMPM Heat Index 400 7 175 2.3 300 4 100 3 200 2 50 4 400 4 100 4 300 2 50 6 400 2 50 8 500 1 25

  8. Control of Reaction Kinetics During Friction Stir Processing

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    Friction stir processing (FSP) was used to successfully embed galfenol particles into aluminum (AA 1100 Al) matrix uniformly. However, intermetallic layer of Al3Fe was formed around the galfenol particles. Activation energy for Al3Fe formation during FSP was estimated, and attempts were made to minimize the Al3Fe layer thickness. By changing the processing conditions, FSP successfully eliminated the intermetallic layer. Hence, FSP, in addition to microstructural control, can successfully fabricate intermetallic-free embedded regions by controlling the reaction kinetics.

  9. Phased array ultrasonic inspection of Friction Stir Weldments

    NASA Astrophysics Data System (ADS)

    Lamarre, André; Moles, Michael; Lupien, Vincent

    2000-05-01

    Phased array ultrasonic inspection methods have been developed for the rapid inspection of Friction Stir Weldments (FSW) on Delta rocket cryogenic tanks. A comprehensive review was performed to identify NDE methods that are suitable for the detection of defects in this new welding process. The search included a review of traditional and advanced NDE methods that were capable of demonstrating both the sensitivity and inspection rates required for this examination. This paper will discuss the theory behind phased array techniques, fundamentals of several probe designs for FSW configurations, and the advantages of using phased arrays over conventional NDE methods for this applications.

  10. 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.

  11. 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.

  12. Control of Reaction Kinetics During Friction Stir Processing

    DOE PAGES

    Das, Shamiparna; Martinez, Nelson Y.; Mishra, Rajiv S.; ...

    2017-02-17

    Friction stir processing (FSP) was used to successfully embed galfenol particles into aluminum (AA 1100 Al) matrix uniformly. But, intermetallic layer of Al3Fe was formed around the galfenol particles. We estimated the activation energy for Al3Fe formation during FSP, and attempts were made to minimize the Al3Fe layer thickness. By changing the processing conditions, FSP successfully eliminated the intermetallic layer. Therefore, FSP, in addition to microstructural control, can successfully fabricate intermetallic-free embedded regions by controlling the reaction kinetics.

  13. 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.

  14. Micromechanical Simulation of Deformation of Friction Stir Welded Components

    NASA Astrophysics Data System (ADS)

    Sidle, B. C.; Dawson, P. R.; Boyce, D. E.

    2004-06-01

    A microstructure-based finite element formulation for the mechanical response of friction stir welded AL-6XN stainless steel is presented. The welding process generates regions of substantial variations in material state and properties that contribute to strong heterogeneities in the mechanical behavior of welded components We modeled the system with a multiscale elastoplastic formulation in which polycrystalline behavior is computed as the integrated responses of constituent crystals. Model validation is made through comparisons to post-test measurements of shape and hardness and to lattice strain measurements from in situ neutron diffraction experiments.

  15. 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.

  16. [Influence of stir-baked with sand on active ingredients, diarrhea and hepatoprotection of Herpetospermum caudigerum].

    PubMed

    Li, Juan-juan; Shen, Gang; Yin, Rong-li; Shen, Cheng-ying; Cheng, Ling; Qiu, Ling; Han, Jin; Yuan, Hai-long

    2015-01-01

    To study the influence of stir-baked with sand on active ingredients, diarrhea and hepatoprotection of Herpetospermum caudigerum, the contents of herperione and herpetin in H. caudigerum before and after stir-baking with sand were analyzed by HPLC. The effect of stir-baked with sand on diarrhea of H. caudigerum TL was evaluated using the mean stool rate (MSR) and mean diarrheal index ( MDI) and the influence of stir-baked with sand on hepatoprotective effect of H. caudigerum TL was examined using a mouse model of CCl4-induced liver injury based on the analysis of serum ALT and AST activities. The results of HPLC analysis showed the content of herperione in H. caudigerum after stir-baking with sand decreased by 40.9% (P < 0.01) and the content of herpetin had no change. Pharmacodynamic results showed that the MSR and MDI of high-dose and middle-dose group of H. caudigerum TL after stir-baking with sand were significantly lower than that of high-dose and middle-dose group of H. caudigerum TL without stir-baking with sand; The high-dose and middle-dose of H. caudigerum TL with/without stir-baking with sand significantly alleviated liver injury as indicated by the decreased levels of serum ALT and AST, but the ALT and AST levels of high-dose and middle-dose group of H. caudigerum TL after stir-baking with sand were higher than that of H. caudigerum TL without stir-baking with sand. The results revealed that the stir-baking with sand could effectively relieve diarrhea effect of H. caudigerum TL, while it also reduces the hepatoprotection of H. caudigerum TL.

  17. Science and politics: free speech controversy at lawrence laboratory.

    PubMed

    Boffey, P M

    1970-08-21

    The Lawrence Radiation Laboratory, one of the nation's most distinguished scientific institutions, has been struck by a series of "free speech" controversies in recent months. The laboratory, which is operated by the University of California and is almost entirely funded by the Atomic Energy Commission, has facilities in two California locations, Berkeley and Livermore. Each has been under fire for allegedly stifling open discussion of controversial issues. The Berkeley facility, a leading center for the study of high-energy physics and fundamental nuclear science, has been split by an internal debate over the right of scientists to hold formal political discussions at the laboratory during their lunch hours. The controversy has led to the banning of meetings, the circulating of petitions and counterpetitions bearing hundreds of names, the publishing of an underground newspaper, and the suspension of a controversial physicist. The Livermore facility, a major center for developing nuclear weapons, has been accused of trying to muzzle two staff scientists who contend that existing radiation standards are too lax to protect the public from nuclear radiation hazards. Livermore has also been the target of demonstrations and of a lawsuit seeking to open the weapons laboratory to allow discussions between outsiders and staff scientists concerning the implications of weapons research. The article below discusses the controversy at the Berkeley laboratory, where only unclassified research is performed. A subsequent article will discuss the conflict at security-conscious Livermore.

  18. 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.

  19. Center Segregation with Final Electromagnetic Stirring in Billet Continuous Casting Process

    NASA Astrophysics Data System (ADS)

    Jiang, Dongbin; Zhu, Miaoyong

    2017-02-01

    With a multiphase solidification model built, the effect of F-EMS parameters on center segregation was investigated in 160 mm × 160 mm billet continuous casting process. In the model, the initial growth of equiaxed grains which could move freely with liquid was treated as slurry, while the coherent equiaxed zone was regarded as porous media. The results show that the stirring velocity is not the main factor influencing center segregation improvement, which is more affected by current intensity and stirring pool width. Because solute transport is controlled by solidification rate as stirring pool width is 73 mm, center segregation declines continuously with current intensity increasing. As liquid pool width decreases to 61 mm and less latent heat needs to dissipate in the later solidification, the center segregation could be improved more obviously by F-EMS. Due to center liquid solute enrichment and liquid phase accumulation in the stirring zone, center segregation turns to rise reversely with higher current intensity and becomes more serious with stirring pool width further decreasing to 43 mm. As the stirring pool width is 25 mm, the positive segregation has already formed and solute could still concentrate with weak stirring, leading to center segregation deterioration. With the optimized current intensity (400 A) and stirring pool width (61 mm) set for continuous mode, center segregation improvement is better than that of alternative mode.

  20. 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.

  1. A Microstructure - Processing Relationships in Friction Stir Processing (FSP) of NiAl Bronze

    DTIC Science & Technology

    2009-02-01

    during straining. Introduction An allied process of friction stir welding [1] ( FSW ), friction stir processing (FSP) is emerging as a novel metal...Robbins, O.C. Shepard and O.D. Sherby: J. Iron Steel Inst., 1964, vol. 202, pp. 804-7 22. O.D. Sherby, B. Walser, C.M. Young and E.M. Cady: Scripta

  2. 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. ...

  3. Dynamics of fluid and light intensity in mechanically stirred photobioreactor.

    PubMed

    Zhang, T

    2013-10-10

    Turbulent flows in a single-stage and a two-stage impeller-stirred photobioreactor with a simple geometric configuration were analyzed using computational fluid dynamics. The trajectories of the microorganisms entrained in the flow field were traced by the particle tracking method. By projecting these trajectories onto a radial-axial (r-z) plane with a given azimuth angle, we were able to observe four different dynamics zones: circulation, pure rotation, trap, and slow-motion. Within the pure rotation zone, turbulence can be observed near the edges of the impeller. The light intensity and the light/dark cycles subjected by the microorganisms differ significantly in these zones. These differences can be further changed by providing different incident light illuminations on the reactor surface. The dynamics zones can be altered by modifying the geometric configuration of the reactor and the impeller stirring mechanism. In combination with the utilization of different incident light illuminations, the light intensity dynamics and the light/dark cycles subjected by the microorganisms can be controlled such that an optimal photobioreactor design with a high efficiency of light utilization and a high formation rate of the biochemical products can be realized.

  4. 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.

  5. 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.

  6. 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

  7. Microstructural Characterizations with EDAX Analysis of Dissimilar Friction Stir Welds

    NASA Astrophysics Data System (ADS)

    Ravikumar, S.; Rao, V. S.

    2013-10-01

    This paper reports the microstructural characteristics of dissimilar friction stir welds with AA7075T651 and AA6061T651. Dissimilar friction stir welds between AA7075T651 and AA6061T651 were produced by varying the rotational speeds between 800 and 1,000 rpm and the welding speeds between 90 and 110 mm/min. The welds were characterized through optical microscope and scanning electron microscope (SEM). Three different tool profiles (taper cylindrical threaded, taper square threaded and simple square) were used for this investigation and in that taper cylindrical threaded tool with process parameters 900 rpm and 100 mm/min were found to have maximum tensile strength of 205 MPa for the dissimilar butt joints. The SEM with energy-dispersive X-ray spectroscopy analysis reveals the metallurgical bonding achieved at the joint interfaces of the welds produced. The good mixing of both the materials joined was obtained at lower welding and higher rotational speed while the tunnel defect was found to be common in the welds produced irrespective of the tool pin profiles and process parameters due to insufficient axial load with 0° tilt angle.

  8. JOINING DISSIMILAR MATERIALS USING FRICTION STIR SCRIBE TECHNIQUE

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep; Fifield, Leonard S.

    2016-09-01

    Development of robust and cost effective method of joining dissimilar materials can provide a critical pathway to enable widespread use of multi-material design and components in mainstream industrial applications. The use of multi-material components such as Steel-Aluminum, Aluminum-Polymer allows design engineers to optimize material utilization based on service requirements and often lead weight and cost reductions. However producing an effective joint between materials with vastly different thermal, microstructural and deformation response is highly problematic using conventional joining and /or fastening methods. This is especially challenging in cost sensitive high volume markets that largely rely on low–cost joining solutions. Friction Stir Scribe technology was developed to meet the demands of joining materials with drastically different properties and melting regimes. The process enables joining of light metals like Magnesium and Aluminum to high temperature materials like Steels and Titanium. Additionally viable joints between polymer composites and metal can also be made using this method. This paper will present state of the art, progress made and challenges associated with this innovative derivative of Friction Stir welding in reference to joining dissimilar metals and polymer/metal combinations.

  9. 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.

  10. Joining Dissimilar Materials Using Friction Stir Scribe Technique

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep; Fifield, Leonard S.

    2016-10-03

    Development of a robust and cost-effective method of joining dissimilar materials could provide a critical pathway to enable widespread use of multi-material designs and components in mainstream industrial applications. The use of multi-material components such as steel-aluminum and aluminum-polymer would allow design engineers to optimize material utilization based on service requirements and could often lead to weight and cost reductions. However, producing an effective joint between materials with vastly different thermal, microstructural, and deformation responses is highly problematic using conventional joining and/or fastening methods. This is especially challenging in cost sensitive, high volume markets that largely rely on low cost joining solutions. Friction stir scribe technology was developed to meet the demands of joining materials with drastically different properties and melting regimes. The process enables joining of light metals like magnesium and aluminum to high temperature materials like steel and titanium. Viable joints between polymer composites and metal can also be made using this method. This paper will present the state of the art, progress made, and challenges associated with this innovative derivative of friction stir welding in reference to joining dissimilar metals and polymer/metal combinations.

  11. The Correlation of Stir Zone Texture Development with Base Metal Texture and Tool-Induced Deformation in Friction Stir Processing of Severely Deformed Aluminum

    NASA Astrophysics Data System (ADS)

    Sarkari Khorrami, M.; Kazeminezhad, Mohsen; Miyashita, Y.; Kokabi, A. H.

    2017-01-01

    The texture development during friction stir processing (FSP) of 1050 aluminum severely deformed at the strain magnitude of 2.32 was comprehensively discussed. It was observed that the component bar{B} of the ideal shear texture along with the cube texture was developed in the severely deformed base metal. The effects of base metal texture on the texture development of stir zone, thermo-mechanically affected zone, and heat-affected zone during FSP were examined. Also, the developed texture components in the vicinity of the FSP tool and the stir zone were correlated to the deformation induced by the rotating tool which consisted of pin and shoulder. The observed texture components in the longitudinal section of the stir zone were found coincided with the ideal shear ones, but different from those observed in the severely deformed base metal. It could be responsible for the fact that the material beneath the FSP tool is predominantly deformed and stirred by the shoulder rather than the pin. The independency of texture development in the stir zone from pin-induced deformation was also consistent with the observation associated with the stir zone geometry which was independent of the pin geometry. Microstructural evolutions in the regions located ahead of the FSP tool manifested the incident of static recovery and recrystallization as a result of the stored strain in the severely deformed base metal. These led to the development of almost random texture and the deterioration of base metal texture in this region. This suggested the independency of texture development in the stir zone from the texture of severely deformed base metal.

  12. Fatigue Performance of Friction-Stir-Welded Al-Mg-Sc Alloy

    NASA Astrophysics Data System (ADS)

    Zhemchuzhnikova, Daria; Mironov, Sergey; Kaibyshev, Rustam

    2017-01-01

    Fatigue behavior of a friction-stir-welded Al-Mg-Sc alloy was examined in cast and hot-rolled conditions. In both cases, the joints failed in the base material region and therefore the joint efficiency was 100 pct. The specimens machined entirely from the stir zone demonstrated fatigue strength superior to that of the base material in both preprocessed tempers. It was shown that the excellent fatigue performance of friction-stir joints was attributable to the ultra-fine-grained microstructure, the low dislocation density evolved in the stir zone, and the preservation of Al3Sc coherent dispersoids during welding. The formation of such structure hinders the initiation and growth of fatigue microcracks that provides superior fatigue performance of friction-stir welds.

  13. 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…

  14. 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.

  15. 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.

  16. Current controversies in the management of breast cancer.

    PubMed

    Tusquets, I; García-Estévez, L; Adrover, E; Calvo, L; Alvarez, I; García Mata, J; Fernández, Y; Margueli, M; Seguí, M A; Muñoz, M; Rodríguez, C; Rodríguez Lescure, A; Colomer, R; Gascón, P; Martín, M; Alba, E; Barnadas, A; Llombart, A; Albanell, J; Lluch, A

    2010-04-01

    The following manuscript summarises the content of the Breast Symposium that was held in May 2008 in Barcelona in which four controversies regarding the management of breast cancer were discussed. The design of the symposium included two speakers per controversy, one in favour and one diverging, and the audience had to vote before and after the presentations to assess changes in the participants' views. The four controversies included: (1) the role of non-conventional predictive factors in selecting treatment for breast cancer; (2) the role of surgery in disseminated disease; (3) are taxanes indicated in the adjuvant treatment of patients with lymph-node-negative disease?; (4) is treatment with tamoxifen (TAM) always required after surgery in patients with ductal carcinoma in situ (DCIS)? The symposium concluded with the presentation titled: 'Features of a well designed clinical trial in the adjuvant treatment of breast cancer'.

  17. 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.

  18. Relational Frame Theory: An Overview of the Controversy

    PubMed Central

    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 can be difficult to fully appreciate, partly because of the complexity of the theory itself and partly because the debate has spanned several years and several journals. The current paper aims to provide a concise overview of RFT and a summary of key points of debate and controversy. PMID:22477432

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

    PubMed

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

    2013-11-08

    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

  20. 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

  1. 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

  2. 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

  3. 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)

  4. Social Reconstruction: The Controversy over the Textbooks of Harold Rugg.

    ERIC Educational Resources Information Center

    Bagenstos, Naida Tushnet

    The paper examines the controversy over the use of Harold Rugg's textbooks in the social studies curriculum during the 1930s and 40s. The first section discusses the philosophy of social reconstruction maintaining that teachers and students should be in the forefront of social change. Rugg's major contribution to social reconstruction was a…

  5. 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…

  6. 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…

  7. 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…

  8. 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…

  9. Financing the UNCED Agenda: The Controversy over Additionality.

    ERIC Educational Resources Information Center

    Jordan, Andrew

    1994-01-01

    Additionality is the concept that developed countries should finance the costs of developing countries to address global environmental problems and make the transition to sustainable development on top of all other financial aid. Discusses the controversy regarding this concept as discussed at the June 1992 United Nations Conference on Environment…

  10. 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…

  11. 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…

  12. 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)

  13. 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…

  14. The Elitist-Populist Controversy: A Response to Ralph Smith.

    ERIC Educational Resources Information Center

    Geahigan, George

    1985-01-01

    The central policy issue in the elitist-populist controversy is what works of art are to be included in curricula. Elitists defend the choice of exemplary pieces of art as instructional materials; populists find this advocacy of exemplars restrictive. How the choice of aesthetic exemplars constitutes a curriculum issue is discussed. (RM)

  15. 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…

  16. 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.…

  17. 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,…

  18. 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…

  19. 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)

  20. 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…

  1. 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…

  2. 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…

  3. D. W. Griffith's Controversial Film, "The Birth of a Nation."

    ERIC Educational Resources Information Center

    Pitcher, Conrad

    1999-01-01

    Presents a lesson plan that enables students to investigate race relations during the Progressive Era by analyzing D. W. Griffith's "The Birth of a Nation" and the controversy surrounding the release of the film. Explores the pros and cons of using motion pictures as teaching tool. Includes two student handouts. (CMK)

  4. Alice Moore and the Kanawha County Textbook Controversy.

    ERIC Educational Resources Information Center

    Kincheloe, Joe

    1980-01-01

    The author considers the 1974 Kanawha County textbook censorship controversy as an attempt by fundamentalist parents to banish "alien" moral influences from the schools and to strengthen community control over learning. He focuses on the role and views of school board member Alice Moore, a leading spokesperson of the fundamentalists.…

  5. 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…

  6. 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…

  7. 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…

  8. 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,…

  9. 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…

  10. 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…

  11. Methods for Addressing Creation/Evolution Controversies in Iowa Schools.

    ERIC Educational Resources Information Center

    Gerlovich, Jack

    Three papers are provided to assist local school districts and legislators in developing their positions when addressing creation/evolution controversies in Iowa schools. "Creation, Evolution and Public Education: The Position of the Iowa Department of Public Instruction (DPI)" presents the consensus of opinions of national and Iowa…

  12. 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…

  13. Controversy Continues over the Pledge of Allegiance. Legal Update

    ERIC Educational Resources Information Center

    McCarthy, Martha M.

    2005-01-01

    Saying the Pledge of Allegiance in public schools has generated controversy for more than sixty years. On Flag Day, June 14, 2004, the U.S. Supreme Court sidestepped an opportunity to clarify the constitutionality of public school students reciting "under God" in the Pledge of Allegiance. But this issue is not going away. Following the Supreme…

  14. Controversies in Spinal Trauma and Evolution of Care.

    PubMed

    Harrop, James S; Rymarczuk, George N; Vaccaro, Alexander R; Steinmetz, Michael P; Tetreault, Lindsay A; Fehlings, Michael G

    2017-03-01

    Management of spinal trauma is a complex and rapidly evolving field. To optimize patient treatment algorithms, an understanding of and appreciation for current controversies and advancing technologies in the field of spinal trauma is necessary. Therefore, members of the AOSpine Knowledge Forum Trauma initiative used a modified Delphi method to compile a list of controversial issues and emerging technologies in the field of spinal trauma, and a list of the 14 most relevant topics was generated. A total of 45 440 manuscripts covering the breadth of spine and spinal trauma were initially identified. This broad search was then refined using the 14 categories felt to be most relevant to the current field of spinal trauma. The results were further pared down using inclusion criteria to select for the most relevant topics. The 8 remaining topics were classification schemes, treatment of vertebral compression fractures, treatment of burst fractures, timing of surgery in spinal trauma, hypothermia, the importance of global sagittal balance, lumbar subarachnoid drainage, and diffusion magnetic resonance imaging. These 8 topics were felt to be the most relevant, controversial, rapidly evolving, and most deserving of inclusion in this summary. In summary, despite recent advances, the field of spinal trauma has many ongoing points of controversy. We must continue to refine our ability to care for this patient population through education, research, and development. It is anticipated that the new AOSpine fracture classification system will assist with prospective research efforts.

  15. Photoprotection: part II. Sunscreen: development, efficacy, and controversies.

    PubMed

    Jansen, Rebecca; Osterwalder, Uli; Wang, Steven Q; Burnett, Mark; Lim, Henry W

    2013-12-01

    In addition to the naturally occurring, physical, and systemic photoprotective agents reviewed in part I, topical ultraviolet radiation filters are an important cornerstone of photoprotection. Sunscreen development, efficacy, testing, and controversies are reviewed in part II of this continuing medical education article.

  16. [The controversy of routine articulator mounting in orthodontics].

    PubMed

    Wang, Li; Han, Xianglong; Bai, Ding

    2013-06-01

    Articulators have been widely used by clinicians of dentistry. But routine articulator mounting is still controversial in orthodontics. Orthodontists oriented by gnathology approve routine articulator mounting while nongnathologic orthodontists disapprove it. This article reviews the thoughts of orthodontist that they agree or disagree with routine articulator mounting based on the considerations of biting, temporomandibular disorder (TMD), periodontitis, and so on.

  17. 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…

  18. 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)

  19. Equal Rights Amendment Controversy: Two Worlds in Conflict.

    ERIC Educational Resources Information Center

    Foss, Sonja K.

    1979-01-01

    The Equal Rights Amendment controversy is studied as a conflict between two world views that are created by the rhetoric generated by proponents and opponents. Descriptions of the settings, actions, characters, and motivations of the opposing worlds reveal little common ground on which traditional argumentation can occur. (JMF)

  20. 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…

  1. 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.…

  2. 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…

  3. [Organic foods and human health: a study of controversies].

    PubMed

    Sousa, Anete Araújo de; Azevedo, Elaine de; Lima, Elinete Eliete de; Silva, Ana Paula Ferreira da

    2012-06-01

    The study of controversies is a methodological tool that generates knowledge about the social and political dimensions of science. This approach can be used to understand and explore the topic of organic foods. The present study aimed to analyze the controversies regarding the status of organic foods. We carried out a review of studies published since 1990 in three websites: International Foundation for Organic Agriculture, Soil Association, and Food and Agriculture Organization. The following controversies were identified: 1) effects on human health of the presence of chemical contaminants in organic foods; 2) the quality of organic foods as compared to conventionally grown foods; and 3) price of organic foods. Based on this review, it is possible to conclude that, even though organic foods stand out for their low toxicity, higher durability, and nutritional content of some items, more comparative studies are required to confirm the nutritional superiority of organic foods and to solve the controversies. The discussion must be contextualized within a broad spectrum of health promotion, in which organic farming appears associated with the support for small farming, biodiversity, and local sustainable development, so as to increase offer and demand for organic products at fair prices for individual and institutional consumers.

  4. MACOS Controversy: Responses to Charges by John Conlan.

    ERIC Educational Resources Information Center

    Dow, Peter B.

    The utility of the controversial elementary social studies program, "Man: A Course of Study" (MACOS), is argued in this paper. A list of 12 charges made by Congressman John Conlan against MACOS, with responses to the charges, is presented. Specific passages in the student materials, films, and teacher materials are examined in context…

  5. Hot Buttons. Unraveling 10 Controversial Issues in Education.

    ERIC Educational Resources Information Center

    Walling, Donovan R., Ed.

    This book is a collection of essays that deal with 10 current controversial issues. The issues are also the topics of 10 recent fastbacks from the Phi Delta Kappa fastback series published between 1993 and 1996. Following the introduction, the articles include the following: (1) "Accountability" (Jack Frymier); (2) "Assessment…

  6. Women, Webquests, and Controversial Issues in the Social Studies

    ERIC Educational Resources Information Center

    Crocco, Margaret Smith; Cramer, Judith

    2005-01-01

    America has been called "the argument culture," but you would not know it from many social studies classrooms. Despite a longstanding tradition in social studies of teaching controversial issues, all too few of today's classrooms accommodate this kind of intellectual activity. Perhaps it is the pressure of high stakes testing, or the emphasis on…

  7. Teaching and Prompting Critical Thinking on Public Controversies.

    ERIC Educational Resources Information Center

    Parker, Walter C.; And Others

    A study was conducted: (1) to determine the proportion of average 6th-grade students who, when given prompts, could produce an incipient form of dialectical reasoning; and (2) to test a unit of instruction developed to teach dialectical reasoning as an appropriate learning strategy for exploring public controversies. It was hypothesized that if…

  8. 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…

  9. 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…

  10. 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…

  11. 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…

  12. 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.

  13. Lunar petrogenesis in a well-stirred magma ocean

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1975-01-01

    The principal group of low-KREEP highlands rocks as indicated by quartz-olivine-anorthite pseudoternary phase diagrams shows chemical trends which violate the Bowen reaction principle, in that the greater the concentration of magnesian and mafic minerals, the more sodic the coexisting plagioclase tends to be. It is suggested that this trend was established during the primary differentiation of the lunar crust and is a result of crystallization in a vigorously convecting (well-stirred) system. Under these conditions all plagioclase crystals, all pyroxene crystals, and all of the residual liquid remain fairly uniform in composition until advanced crystallization immobilizes the system. The rock suite then established would vary continuously from anorthositic types at the top to ultramafic types at the bottom.

  14. Stirring with ghost rods in a lid-driven cavity

    NASA Astrophysics Data System (ADS)

    Kumar, Pankaj; Chen, Jie; Stremler, Mark

    2009-11-01

    It has shown that passive fluid particles moving on periodic orbits can be used to `stir' a viscous fluid in a two-dimensional lid-driven cavity that exhibits a figure-eight flow pattern (Stremler & Chen 2007). Fluid motion in the vicinity of these particles produces ``ghost rod'' structures that behave like semi-permeable rods in the flow. Since these ghost rods are present due to the system dynamics, perturbations in the boundary conditions lead to variations in the existence and structure of the ghost rods. We discuss these variations and assess the role of ghost rods in mixing over a range of operating conditions for this system. The results suggest that ghost rods can play an important role in mixing for other counter-rotating flows.

  15. New insights on oxygen absorption in unsparged stirred vessels

    NASA Astrophysics Data System (ADS)

    Averkina, A. S.; Kazakov, D. A.; Asnin, L. D.; Kaczmarski, K.; Krol, G.; Vol'khin, V. V.

    2016-12-01

    A combination of experimental and numerical techniques revealed subtle features of oxygen absorption in unsparged stirred vessels. It was shown that the absorption kinetics was influenced not only by the mass transfer resistance in the gas-liquid interface but also by imperfect mixing in the bulk liquid. The liquid's viscosity and density were suggested to affect the oxygen mass transfer by influencing the turbulence both at the surface and in the bulk phase, while the modification of the surface layer through surfactant addition affected only surface turbulence. The axial dispersion model proved good in the explanation of the experimental results. For the sake of comparison, the classical stagnant film model was also tested but led to slight, yet systematic, deviations in its predictions from the experimental data.

  16. Lateral position detection and control for friction stir systems

    SciTech Connect

    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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Friction Stir Welding of ODS and RAFM Steels

    DOE PAGES

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; ...

    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

  6. Stir bar sorptive extraction: recent applications, limitations and future trends.

    PubMed

    Camino-Sánchez, F J; Rodríguez-Gómez, R; Zafra-Gómez, A; Santos-Fandila, A; Vílchez, J L

    2014-12-01

    Stir bar sorptive extraction (SBSE) has generated growing interest due to its high effectiveness for the extraction of non-polar and medium-polarity compounds from liquid samples or liquid extracts. In particular, in recent years, a large amount of new analytical applications of SBSE has been proposed for the extraction of natural compounds, pollutants and other organic compounds in foods, biological samples, environmental matrices and pharmaceutical products. The present review summarizes and discusses the theory behind SBSE and the most recent developments concerning its effectiveness. In addition, the main results of recent analytical approaches and their applications, published in the last three years, are described. The advantages, limitations and disadvantages of SBSE are described and an overview of future trends and novel extraction sorbents and supports is given.

  7. Joining dissimilar materials using Friction Stir scribe technique

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep; Fifield, Leonard S.

    2016-10-03

    The ability to effectively join materials with vastly different melting points like Aluminum-Steel, Polymer composites - metals has been one of the road blocks in realizing multi-material components for light weighting efforts. Friction stir scribe (FSS) technique is a promising method that produces continuous overlap joint between materials with vastly different melting regimes and high temperature flow characteristics. FSS uses an offset cutting tool at the tip of the FSW pin to create an insitu mechanical interlock between material interfaces. With investments from Vehicle Technology office, US DOE and several automotive manufacturers and suppliers PNNL is developing the FSS process and has demonstrated viability of joining several material combinations. Details of welding trails, unique challenges and mitigation strategies in different material combinations will be discussed. Joint characterization including mechanical tests and joint performances will also be presented.

  8. Grain size reduction by electromagnetic stirring inside gold alloys

    NASA Astrophysics Data System (ADS)

    Ernst, R.; Mangelinck-Noël, N.; Hamburger, J.; Garnier, C.; Ramoni, P.

    2005-06-01

    The final properties of cast materials depend greatly on the solidification process undergone by the material. In this paper, we study gold alloys dedicated to the watch industry and jewellery in the framework of a research collaboration with the Metalor Company. The aim is to improve the concentration homogeneity of the ingots by controlling the solidification step. It can be achieved by reducing segregations by a decrease in the grain size. For this purpose, we set up a multiphase electromagnetic stirring of the melt to favour the growth of finer grains and improve the homogeneity of the composition. We first design an electromagnetic stirrer by numerical simulation. The stirrer is then implemented on a model experiment. Eventually, the alloys are characterised by metallography and etching to evidence the grain structure. As expected, we obtain a substantial reduction of the grain size although, some work remains to be done to attain the final goal of even finer grains.

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

    NASA Astrophysics Data System (ADS)

    Yakubu, Aisha Aliyu; Yatim, Yazariah Mohd

    2015-10-01

    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.

  10. 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

  11. 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.

  12. 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.

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

    DOE PAGES

    Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; ...

    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

  14. 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.

  15. Investigation of Machine Design for Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Romine, Peter L.

    1996-01-01

    The process of joining two pieces of metal together has not significantly changed over the last few decades. The basic idea used is to bring the pieces together and apply enough heat to melt the metal at the interface. The molten metal mixes and after cooling forms a strong joint. This process is called the fusion process. The most significant difference between the many fusion processes is how the heat is generated and applied. The Welding Institute (TWI), in Great Britain, has recently patented an innovative application of mechanical friction. TWI designed a tool and process called Friction Stir Welding (FSW) that uses friction to heat the metal to within a few hundred degrees Fahrenheit of melting, just to the point of being plastic-like. The tool then stirs the plasticized metal together forming a joint that has been shown to be as good or better than an equivalent fusion joint. The FSW process is well suited for the joining of the aluminum alloys used in the aerospace industry. The relatively low melting point of aluminum eliminates the requirements for exotic materials for pin tool design. The FSW process has been successfully used to join alloys such as 7075 which were before considered "unweldable", and aluminum-lithium 2195 which exhibits many problems when fusion welded. The objective this summer was to investigate the design of a FSW system that could take this process from the laboratory to the manufacturing floor. In particular, it was the goal of my NASA colleague to develop a concept for applying the FSW process to the manufacturing of aluminum cryogenic oxygen and hydrogen tanks, of the sort used to make the Shuttle External Tank.

  16. 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.

  17. Bulk viscosity of stirred xenon near the critical point

    NASA Astrophysics Data System (ADS)

    Gillis, K. A.; Shinder, I. I.; Moldover, M. R.

    2005-11-01

    We deduce the thermophysical properties of near-critical xenon from measurements of the frequencies and half-widths of the acoustic resonances of xenon maintained at its critical density in centimeter-sized cavities. In the reduced temperature range 1×10-3<(T-Tc)/Tc<7×10-6 , we measured the resonance frequency and quality factor (Q) for each of six modes spanning a factor of 27 in frequency. As Tc was approached, the frequencies decreased by a factor of 2.2 and the Q ’s decreased by as much as a factor of 140. Remarkably, these results are predicted (within ±2% of the frequency and within a factor of 1.4 of Q ) by a model for the resonator and a model for the frequency-dependent bulk viscosity ζ(ω) that uses no empirically determined parameters. The resonator model is based on a theory of acoustics in near-critical fluids developed by Gillis, Shinder, and Moldover [Phys. Rev. E 70, 021201 (2004)]. In addition to describing the present low-frequency data (from 120Hzto7.5kHz ), the model for ζ(ω) is consistent with ultrasonic (0.4-7MHz) velocity and attenuation data from the literature. However, the model predicts a peak in the temperature dependence of the dissipation in the boundary layer that we did not detect. This suggests that the model overestimates the effect of the bulk viscosity on the thermal boundary layer. In this work, the acoustic cavities were heated from below to stir the xenon, thereby reducing the density stratification resulting from Earth’s gravity. The stirring reduced the apparent equilibration time from several hours to a few minutes, and it reduced the effective temperature resolution from 60mK to approximately 2mK , which corresponds to (T-Tc)/Tc≈7×10-6 .

  18. 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.

  19. 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.

  20. Tensile strength on friction stir processed AMg5 (5083) aluminum alloy

    NASA Astrophysics Data System (ADS)

    Chumaevsky, A. V.; Eliseev, A. A.; Filippov, A. V.; Rubtsov, V. E.; Tarasov, S. Yu.

    2016-11-01

    The results of the tensile tests carried out both on AMg5 (5083) aluminum alloy samples base and those obtained using friction stir processing technique are reported. The tensile test samples have been prepared from the friction stir processed plates so that their tensile axis was parallel to the processing direction. The maximum tensile strength of the processed samples was 9% higher than of the base metal. The fractographic examination shows the presence of flat areas inherent of the brittle fracture in all three friction processed samples. The load-extension curves show that friction stir processing may suppress the serrated yielding.

  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. 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.

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

    DOE PAGES

    Yu, Xinghua; Mazumder, B.; Miller, M. K.; ...

    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. Nosocomial pneumonia in the intensive care unit: controversies and dilemmas.

    PubMed

    Mehta, Ravindra M; Niederman, Michael S

    2003-01-01

    Nosocomial pneumonia (NP), and its most serious form, ventilator-associated pneumonia (VAP), is a major cause of morbidity and mortality in the ICU. Numerous controversies exist, from diagnostic criteria to prevention and treatment, including the issues of attributable mortality of VAP, differences in the approach to early and late VAP, and the best diagnostic methods. Initial, accurate therapy is one of the most important factors determining outcome in VAP. Antibiotic monotherapy versus combination therapy is not clearly defined, as clinicians struggle with the dual risk of inadequate therapy negatively affecting outcome and overtreatment promoting antibiotic resistance. The role of airway and gastrointestinal colonization and innovative preventive strategies such as noninvasive ventilation, antibiotic rotation, and aerosolized antibiotics are discussed. No uniform standards exist for the approach to VAP. The authors highlight the major controversies and dilemmas in the clinical approach to VAP, with recommendations for the bedside management of these patients.

  7. Distinguishing heat from light in debate over controversial fossils.

    PubMed

    Donoghue, Philip C J; Purnell, Mark A

    2009-02-01

    Fossil organisms offer our only direct insight into how the distinctive body plans of extant organisms were assembled. However, realizing the potential evolutionary significance of fossils can be hampered by controversy over their interpretation. Here, as a guide to evaluating palaeontological debates, we outline the process and pitfalls of fossil interpretation. The physical remains of controversial fossils should be reconstructed before interpreting homologies, and choice of interpretative model should be explicit and justified. Extinct taxa lack characters diagnostic of extant clades because the characters had not yet evolved, because of secondary loss, or because they have rotted away. The latter, if not taken into account, will lead to the spurious assignment of fossils to basally branching clades. Conflicting interpretations of fossils can often be resolved by considering all the steps in the process of anatomical analysis and phylogenetic placement, although we must accept that some fossil organisms are simply too incompletely preserved for their evolutionary significance to be realized.

  8. Chemoradiation for rectal cancer: rationale, approaches, and controversies.

    PubMed

    Minsky, Bruce D

    2010-10-01

    The standard adjuvant treatment of cT3 and/or N+ rectal cancer is preoperative chemoradiation. However, there are many controversies regarding this approach. These controversies include the role of short course radiation, whether postoperative adjuvant chemotherapy is necessary for all patients, and if the type of surgery following chemoradiation should be based on the response rate. More accurate imaging techniques and/or molecular markers may help identify patients with positive pelvic nodes to reduce the chance of overtreatment with preoperative therapy. Will more effective systemic agents both improve the results of radiation, as well as modify the need for pelvic radiation? These questions and others remain active areas of clinical investigation.

  9. 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.

  10. 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

  11. 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.

  12. Mercury, vaccines, and autism: one controversy, three histories.

    PubMed

    Baker, Jeffrey P

    2008-02-01

    The controversy regarding the once widely used mercury-containing preservative thimerosal in childhood vaccines has raised many historical questions that have not been adequately explored. Why was this preservative incorporated in the first place? Was there any real evidence that it caused harm? And how did thimerosal become linked in the public mind to the "autism epidemic"? I examine the origins of the thimerosal controversy and their legacy for the debate that has followed. More specifically, I explore the parallel histories of three factors that converged to create the crisis: vaccine preservatives, mercury poisoning, and autism. An understanding of this history provides important lessons for physicians and policymakers seeking to preserve the public's trust in the nation's vaccine system.

  13. 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

  14. Acute disseminated encephalomyelitis: current controversies in diagnosis and outcome.

    PubMed

    Koelman, Diederik L H; Mateen, Farrah J

    2015-09-01

    Acute disseminated encephalomyelitis (ADEM) is a rare inflammatory, demyelinating disorder of the CNS. Only in the past 15 years have larger groups of patients from several geographical areas been reported for comparisons across studies. In spite of the increased recognition of ADEM, the diagnosis of ADEM remains clinical, aided by neuroimaging confirmation, because of the lack of a biological marker. The diagnosis may be difficult, given that several diseases may present similar to ADEM. The controversial existence of multiphasic forms necessitates a continuous evaluation of the diagnosis by tracking subsequent events. Despite proposed consensus criteria, the diagnostic criteria employed to characterize ADEM range widely among the largest reported cohorts to date. This review comprehensively evaluates the current knowledge and controversies that surround ADEM, with special consideration of the distinction between ADEM and other demyelinating diseases such as multiple sclerosis. In addition, we present implications of the current knowledge of ADEM for both research and clinical practice.

  15. Socio-scientific controversies and students' conceptions about scientists

    NASA Astrophysics Data System (ADS)

    Reis, Pedro; Galvão, Cecília

    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 involving a group of scientists working on a particular situation of her/his choice. Next, semi-structured interviews were carried out to clarify and discuss the ideas embodied in the stories and mentioned in the questionnaire. All data underwent a process of content analysis. The socio-scientific controversies recently discussed, and the way science and scientists are depicted in the media, seem to have produced some impact on students' conceptions about scientists. Based on the results obtained, some remarks and educational implications are discussed.

  16. Controversies in the management of primary sclerosing cholangitis

    PubMed Central

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

    2016-01-01

    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

  17. Current controversies in clinical management of postmenopausal osteoporosis.

    PubMed

    Kerschan-Schindl, K; Mikosch, P; Obermayer-Pietsch, B; Gasser, R W; Dimai, H-P; Fahrleitner-Pammer, A; Dobnig, H; Roschger, P; Preisinger, E; Klaushofer, K; Resch, H; Pietschmann, P

    2014-09-01

    Osteoporosis is a frequent disease in postmenopausal women. Despite the fact that fragility fractures cause many problems - a bio-psycho-social burden for the individual and an economic burden for the society - osteoporosis is still underdiagnosed and undertreated. Controversies exist concerning assessment with different tools for initiating a disease-specific treatment, patient monitoring with bone turnover markers, and treatment duration due to potential side effects in long-term treatment. This manuscript outlines and discusses these controversies and the presented cases, representatives for frequent clinical problems, may give guidance for the clinician in deciding how and how long to treat his/her patient. Re-evaluations of the patients on a regular basis are essential to warrant the necessity of treatment continuation and may improve patients' compliance.

  18. Effects of mechanical force on grain structures of friction stir welded oxide dispersion strengthened ferritic steel

    NASA Astrophysics Data System (ADS)

    Han, Wentuo; Kimura, Akihiko; Tsuda, Naoto; Serizawa, Hisashi; Chen, Dongsheng; Je, Hwanil; Fujii, Hidetoshi; Ha, Yoosung; Morisada, Yoshiaki; Noto, Hiroyuki

    2014-12-01

    The weldability of oxide dispersion strengthened (ODS) ferritic steels is a critical obstructive in the development and use of these steels. Friction stir welding has been considered to be a promising way to solve this problem. The main purpose of this work was to reveal the effects of mechanical force on grain structures of friction stir welded ODS ferritic steel. The grain appearances and the misorientation angles of grain boundaries in different welded zones were investigated by the electron backscatter diffraction (EBSD). Results showed that the mechanical force imposed by the stir tool can activate and promote the recrystallization characterized by the transformation of boundaries from LABs to HABs, and contribute to the grain refinement. The type of recrystallization in the stir zone can be classified as the continuous dynamic recrystallization (CDRX).

  19. Preparation of fenofibrate nanoparticles by combined stirred media milling and ultrasonication method.

    PubMed

    Patel, Chetankumar M; Chakraborty, Mousumi; Murthy, Z V P

    2014-05-01

    The production of fenofibrate nanoparticles combining stirred media milling and ultrasonication method was investigated in the current work. The fenofibrate drug sample was first wet milled in stirred media mill for different times and subsequently processed by ultrasonication. The effects of ultrasonication time, power on final product particle sizes were studied. The pre milling by stirred media milling was resulted into reduction of comminution resistance of material. Subsequent treatment by ultrasonication produced smaller particles than obtained by stirred media milling alone. The resulting nanoparticles were found to exhibit excellent stability as investigated by particle size, zeta potential, and multiple light scattering measurement techniques. Further, qualities of nanoparticles obtained by combined approach were characterized by TEM and XRD analysis.

  20. STIR Version 1.0 User's Guide for Pesticide Inhalation Risk

    EPA Pesticide Factsheets

    STIR estimates inhalation-type exposure based on pesticide-specific information. It also estimates spray droplet exposure using the application method and rate and then compares these exposure estimates to avian and mammalian toxicity data.

  1. 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.

  2. Controversies and challenges of vaccination: an interview with Elizabeth Miller.

    PubMed

    Miller, Elizabeth

    2015-10-16

    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.

  3. 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.

  4. Surgical Treatment of Epiphrenic Diverticulum: Technique and Controversies.

    PubMed

    Andolfi, Ciro; Wiesel, Ory; Fisichella, P Marco

    2016-11-01

    The goal of this article is to illustrate the current minimal invasive approaches to patients with epiphrenic diverticulum in terms of preoperative evaluation, surgical technique, and outcomes. Two techniques will be presented: a laparoscopic and a video-assisted thoracic repair. Indications for each technique will be discussed as well as proper patient selection and management. Current controversies in the treatment of patients with this rare disease will be addressed.

  5. 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

  6. Zollinger-Ellison syndrome: past, present and future controversies.

    PubMed Central

    Jensen, R. T.

    1994-01-01

    It is fitting that the Zollinger-Ellison syndrome (ZES) be included in the Lester Dragstedt Symposium because Dr. Dragstedt had a long-time interest in this disease, having been one of the five discussants of the original article and subsequently reporting with Dr. Oberhelman on nine cases. The approach to therapy of ZES has been controversial from the beginning, and a number of controversies remain. In this article, four different controversies are analyzed from the prospective of the past (Zollinger-Dragstedt era, 1955-1980), present and what may happen in the future in light of recent results. Specifically analyzed are: 1) the role of gastric surgery in the management; 2) whether gastrinoma removal without aggressive resection in patients with ZES without MEN-I is the preferred surgical therapy; 3) whether patients with MEN-I should undergo routine surgical exploration; and 4) whether most gastrinomas will be localized preoperatively. An analysis of recent advances suggests there may be marked changes in the future from our current and our past approaches. Images Figure 2 PMID:7502529

  7. The controversy over the minimum quantum requirement for oxygen evolution.

    PubMed

    Hill, Jane F; Govindjee

    2014-10-01

    During the early- to mid-twentieth century, a bitter controversy raged among researchers on photosynthesis regarding the minimum number of light quanta required for the evolution of one molecule of oxygen. From 1923 until his death in 1970, Otto Warburg insisted that this value was about three or four quanta. Beginning in the late 1930s, Robert Emerson and others on the opposing side consistently obtained a value of 8-12 quanta. Warburg changed the protocols of his experiments, sometimes in unexplained ways, yet he almost always arrived at a value of four or less, except eight in carbonate/bicarbonate buffer, which he dismissed as "unphysiological". This paper is largely an abbreviated form of the detailed story on the minimum quantum requirement of photosynthesis, as told by Nickelsen and Govindjee (The maximum quantum yield controversy: Otto Warburg and the "Midwest-Gang", 2011); we provide here a scientific thread, leaving out the voluminous private correspondence among the principal players that Nickelsen and Govindjee (2011) examined in conjunction with their analysis of the principals' published papers. We explore the development and course of the controversy and the ultimate resolution in favor of Emerson's result as the phenomenon of the two-light-reaction, two-pigment-system scheme of photosynthesis came to be understood. In addition, we include a brief discussion of the discovery by Otto Warburg of the requirement for bicarbonate in the Hill reaction.

  8. 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.

  9. Studies of Stirring and Mixing at the Submesoscale in the Ocean: FY2013 Annual Report

    DTIC Science & Technology

    2013-09-30

    Studies of stirring and mixing at the submesoscale in the ocean: FY2013 Annual Report Raffaele Ferrari Department of Earth, Atmospheric and...Turbulence” DRI, our goal is to understand and quantify the stirring and mixing of submesoscale tracers by turbulent processses at the mesoscale and... submesoscale . Our intention is to both delineate the fundamental processes at work, and to guide the interpretation of tracer release, hydrographic

  10. 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

  11. Microstructural Effects of Multiple Passes during Friction Stir Processing of Nickel Aluminum Bronze

    DTIC Science & Technology

    2009-12-01

    various tool steel compositions for use with aluminum , and materials such as Densimet®, a tungsten-iron composite. Additionally, various other...TMAZ. 5 II. BACKGROUND INFORMATION A. FRICTION STIR PROCESSING To this date, FSP and FSW have been used most extensively on aluminum -based...EFFECTS OF MULTIPLE PASSES DURING FRICTION STIR PROCESSING OF NICKEL ALUMINUM BRONZE by Elizabeth A. Nelson December 2009 Thesis Advisor

  12. Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications

    DTIC Science & Technology

    2012-12-01

    production-level, single-pass friction stir welding ( FSW ) parameters for thicknesses ranging from 0.5 to 1.6 inches in aluminum alloys 5083, 5059, and 2139...developing thick section aluminum Friction Stir Welding ( FSW ) for use in aluminum military vehicle applications. The primary objective of this...this demonstration article represents a significant step forward in the acceptance of FSW technology as a viable joining method for aluminum hulled

  13. Control of Structure in Conventional Friction Stir Welds Through a Kinematic Theory of Metal Flow

    DTIC Science & Technology

    2009-02-01

    suggested a “chaotic-dynamic mixing” in the material [2]. Later tracer studies, using steel shot [3], aluminum shims [4], copper foil [5], bi-metallic...35812 Keywords: friction stir welding, AA2219, material flow Abstract In friction stir welding ( FSW ), a rotating pin is translated along a...welding, by a shoulder on the pin. In conventional FSW , the weld metal rests on an “anvil”, which supports the heavy “plunge” load on the tool. In

  14. Microstructural Investigation and Evaluation of Mechanical Properties in Friction Stir Welded Joints

    DTIC Science & Technology

    2011-08-01

    collegiate lecturer. 175 1. Introduction/Background Aluminum is becoming an increasingly desirable structural metal for replacing steel due to...is needed. Friction stir welding ( FSW ) is a solid-state joining technique developed in 1991 (1) and currently used extensively in aluminum alloys...Typical Aluminum FSW Tool 176 are a result of dynamic recrystallization and are very dependent on the stir parameters. Hirata et al. (3) showed that

  15. The "Lazy S" Feature in Friction Stir Welding of AA2099 Aluminum -Lithium Alloy

    DTIC Science & Technology

    2007-12-01

    stiffness and strength , and so these materials are attractive for selected aerospace structures . Friction Stir Welding (FSW) of Al-Li alloys may...process, FSW uses a combination of extruding and forging at temperatures well below the melting point of the material to form a high- strength bond ...deformation. The randomness of grain size and structure throughout the stir nugget is the same and supports the presence of a shear texture. The

  16. Observations of Tool-Workpiece Interactions during Friction Stir Processing of Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Pilchak, A. L.; Juhas, M. C.; Williams, J. C.

    2007-02-01

    Significant tool wear manifested as submicron tungsten-rich particles was observed in the workpiece after friction stir processing (FSP) of investment cast Ti-6Al-4V on both the surface and in the bulk of the stir zone. The tool was manufactured from a tungsten alloy, which stabilizes the β phase and can locally suppress the β transus. A postprocessing α/β heat treatment was performed to demonstrate the microstructure effects of tungsten dissolution.

  17. Marine ecosystem dynamics, ocean circulation and horizontal stirring

    NASA Astrophysics Data System (ADS)

    Rossi, V.; Tewkai, E.; López, C.; Sudre, J.; Hernández-García, E.; Garcon, V.

    2009-04-01

    The oceanic submeso and mesoscale circulation and its eddies, filaments, meanders play a major role in marine ecosystems dynamics from the lower trophic levels to the marine top predators. We study here the interplay between turbulence in fluid dynamics on these scales and biological activity at different trophic levels using two cases study. The first example focuses on the four eastern boundary upwelling zones, the Canary, Benguela, California and Humboldt upwelling systems which constitute the largest contribution to the world ocean productivity. These areas are spatially heterogeneous, populated with a large variety of mesoscale and sub-mesoscale structures such as filaments, plumes and eddies, which control exchange processes between the shelf and open ocean and play a major role in modulating the biomass, rates and structure of marine ecosystems. We will present here results from a lagrangian approach based on Finite Size Lyapunov Exponents (FSLE) using altimetric and scatterometric data to estimate the spatial and temporal variations in the lateral stirring and mixing of tracers in the upper ocean within the four areas. When investigating links with chlorophyll a concentration as a proxy for biological activity in these upwelling systems, results show that surface horizontal stirring and mixing vary inversely with chlorophyll standing stocks. FSLEs lead to a clear clustering of the systems suggesting that one may use them as integrated and comparative indices for characterizing horizontal dynamical features in all eastern boundary upwellings. Then we investigate the role of submesoscale structures in the Mozambique Channel on the distribution of a top marine predator, the Great Frigatebird. Using similar dynamical concept, the FSLE, we have identified Lagrangian Coherent Structures (LCSs) present in the surface flow in the Channel. By comparing seabirds' satellite positions with LCSs locations, we demonstrate that frigatebirds track precisely these

  18. 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

  19. Finite-temperature effects in stirred ring Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Murray, N.; Lanier, C.; Edwards, M.; Wang, Y.-H.; Clark, C. W.

    2014-05-01

    A ring Bose-Einstein condensate (BEC) with zero circulation (m = 0) stirred by a barrier will eventually jump to an m = 1 state when stirred faster than a certain critical speed, Ωc+. A ring BEC with m = 1 will drop to m = 0 when stirred at a critical speed, Ωc-, which is lower than Ωc+. The loop areas, Ωc+ -Ωc- , of this hysteretic response of the BEC to stirring predicted by zero-temperature Gross-Pitaevskii equation (GPE) disagreed significantly with the results of a recent experiment. In the work reported here, we simulated this experiment with the phenomenologically damped GPE, [S. Choi, S. A. Morgan, and K. Burnett, Phys. Rev. A 57, 4057 (1999)], and with the Zaremba-Nikuni-Griffin (ZNG) theory. The ZNG theory can account for finite-T, non-equilibrium dynamics. We compare the results of these simulations with the experimental data. The simulations show that a vortex/antivortex pair forms in the barrier region during the stirring and that this drives the hysteresis. We also show how the presence of an interacting, thermal cloud affects the dynamics of these pairs. We also simulate a ring condensate stirred by two barriers and find that the GPE matches the data much more closely. Supported in part by NSF grant #1068761 and ARO Atomtronics MURI.

  20. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    NASA Astrophysics Data System (ADS)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide - cobalt chromium, chromium carbide - nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the MMC aligns with the improved dispersion of reinforcing particles throughout the aluminium matrix.

  1. 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.

  2. Hybrid manufacturing processes for fusion welding and friction stir welding of aerospace grade aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gegesky, Megan Alexandra

    Friction stir welding and processing can provide for joints in aerospace grade aluminum alloys that have preferable material properties as compared to fusion welding techniques. Aerospace grade aluminum alloys such as AA2024-T3 and AA7075-T6 are considered non-weldable by traditional fusion welding techniques. Improved mechanical properties over previously used techniques are usually preferable for aerospace applications. Therefore, by combining traditional fusion welding and friction stir processing techniques, it could be plausible to create more difficult geometries in manufactured parts instead of using traditional techniques. While this combination of fusion welding and friction stir processing is not a new technology, its introduction to aerospace grade aluminum alloys as well as non-weldable alloys, is new. This is brought about by a lowered required clamping force required by adding a fusion weld before a friction stir processing technique. The changes in properties associated with joining techniques include: microstructural changes, changes in hardness, tensile strength, and corrosion resistance. This thesis illustrates these changes for the non-weldable AA2024-T351 and AA7075-T651 as well as the weldable alloy AA5052-H32. The microhardness, tensile strength and corrosion resistance of the four processing states: base material, fusion welded material, friction stir welded material, and friction stir processed fusion welded material is studied. The plausibility of this hybrid process for the three different materials is characterized, as well as plausible applications for this joining technique.

  3. 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.

  4. Influence of proteins on the perception of flavored stirred yogurts.

    PubMed

    Saint-Eve, A; Lévy, C; Martin, N; Souchon, I

    2006-03-01

    Among yogurt dairy components, protein type is known to modify the texture of the products and the volatility of odorous volatile organic compounds. The aim of this study was to investigate the impact of 3 protein ratios (caseinate to total protein) on the sensory properties of 4% fat, strawberry-flavored stirred yogurts. A sensory methodology study was therefore investigated to choose the most efficient method in terms of sensitivity, quantification, and ease with which the panel could distinguish slight differences in olfactory property between the yogurts. Three kinds of product presentation procedures were compared: a monadic presentation, a comparative presentation, and a comparative presentation with a reference. The results showed that the 3 presentation methods emphasized some important texture differences between the yogurts in the same way. However, the comparative procedure with a reference was the only one to reveal clear olfactory property differences between the yogurts. The main effect of protein ratio variation in yogurt concerned the texture properties, which greatly differed between the 3 yogurts and was confirmed by complex viscosity measurements. Olfactory differences between the yogurts were more subtle. Overall, the flavor intensity and the fruity notes were less intense in the yogurts with the high caseinate ratio than in those with the low ratio. This result was in agreement with the physicochemical measurements, which showed a higher retention of a large majority of aroma compounds of the strawberry flavor in the yogurts with a high caseinate ratio.

  5. Mixing times in a stirred vessel with a modified turbine.

    PubMed

    Bombač, Andrej; Beader, Dečan; Zun, Iztok

    2012-12-01

    We present a mixing-time analysis for a double-disk turbine (DDT, SI Pat.No. 22243) and the well-known Rushton turbine (RuT) based on liquid stirring in a baffled vessel. The mixing time was measured locally based on the pulse/response technique. A small quantity of hot water, poured into the liquid bulk, just above the measurement location, was used as the pulse, while the change in the liquid temperature represented the system response. The results were obtained in two ways: (i) from measurements on the set-up and (ii) based on a CFD analysis. The pouring of the hot water was numerically simulated through the initialization of the scalar field. The duration of the temperature-pulse initialization around the measuring location corresponded to the pouring time in the experiment. All the energy introduced was freely swept away by the flow. The CFD-analyzed mixing times were consistently higher than the measured ones across the whole testing range, from 150 to 460 min-1. When comparing our mixing-time results with those from the literature based on a dimensionless mixing time we found them to be in good agreement.

  6. 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.

  7. Springback evaluation of friction stir welded TWB automotive sheets

    NASA Astrophysics Data System (ADS)

    Kim, Junehyung; Lee, Wonoh; Chung, Kyung-Hwan; Kim, Daeyong; Kim, Chongmin; Okamoto, Kazutaka; Wagoner, R. H.; Chung, Kwansoo

    2011-02-01

    Springback behavior of automotive friction stir welded TWB (tailor welded blank) sheets was experimentally investigated and the springback prediction capability of the constitutive law was numerically validated. Four automotive sheets, aluminum alloy 6111-T4, 5083-H18, 5083-O and dual-phase DP590 steel sheets, each having one or two different thicknesses, were considered. To represent mechanical properties, the modified Chaboche type combined isotropic-kinematic hardening law was utilized along with the non-quadratic orthogonal anisotropic yield function, Yld2000-2d, while the anisotropy of the weld zone was ignored for simplicity. For numerical simulations, mechanical properties previously characterized [1] were applied. For validation purposes, three springback tests including the unconstrained cylindrical bending, 2-D draw bending and OSU draw-bend tests were carried out. The numerical method performed reasonably well in analyzing all verification tests and it was confirmed that the springback of TWB as well as of base samples is significantly affected by the ratio of the yield stress with respect to Young's modulus and thickness.

  8. Threshold for creating excitations in a stirred superfluid ring

    NASA Astrophysics Data System (ADS)

    Wright, K. C.; Blakestad, R. B.; Lobb, C. J.; Phillips, W. D.; Campbell, G. K.

    2013-12-01

    We have measured the threshold for creating long-lived excitations when a toroidal Bose-Einstein condensate is stirred by a rotating (optical) barrier of variable height. When the barrier height is on the order of or greater than half of the chemical potential, the critical barrier velocity at which we observe a change in the circulation state is much less than the speed for sound to propagate around the ring. In this regime we primarily observe discrete jumps (phase slips) from the noncirculating initial state to a simple, well-defined, persistent current state. For lower barrier heights, the critical barrier velocity at which we observe a change in the circulation state is higher, and approaches the effective sound speed for vanishing barrier height. The response of the condensate in this small-barrier regime is more complex, with vortex cores appearing in the bulk of the condensate. We find that the variation of the excitation threshold with barrier height is in qualitative agreement with the predictions of an effective one-dimensional hydrodynamic model.

  9. NDE of Friction Stir Welds in Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Kinchen, David G.; Aldahir, Esma

    2002-01-01

    Friction Stir Welding (FSW) is a solid state joining process, which utilizes a cylindrical, shouldered pin tool with a radiused tip that is rotated and plunged into the weld joint. Frictional heating beneath the shoulder, and surrounding the pin tip causes the material to plasticize, intermix and consolidate into a weldment without melting the parent material. FSW in aluminum alloys has many advantages such as low distortion and shrinkage, excellent mechanical properties, and no porosity. However, the propensity of the FSW process to create detrimental defects does exist, and is dependent on FSW parameter limits and controls. Inspection processes for FSW must also be selected and implemented concurrent with the new weld process. This paper describes the efforts by Lockheed Martin and NASA to find proper NDE techniques for detecting and characterizing the anomalies that may be caused by operating outside the envelope of optimized FSW parameters. Potential defects are identified and the results of the exploration of numerous NDE techniques including visual, liquid penetrant, multiple ultrasonic methods, eddy current and conductivity are discussed.

  10. 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.

  11. 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.

  12. 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.

  13. Al-to-Cu Friction Stir Lap Welding

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid; Kou, Sindo

    2012-01-01

    Recently, friction stir welding (FSW) has been used frequently to join dissimilar metals, for instance, Al to Mg, Cu, and steel. The formation of brittle intermetallic compounds often severely limits the strength and ductility of the resultant welds. In the present study, Al-to-Cu lap FSW was studied by welding 6061 Al to commercially pure Cu. Conventional lap FSW was modified by butt welding a small piece of Al to the top of Cu, with a slight pin penetration into the bottom of Al. At travel speeds up to 127 mm/min (5 ipm), the modified welds were about twice the joint strength and five to nine times the ductility of the conventional lap welds. In the conventional lap welds, voids were present along the Al-Cu interface, and fracture occurred along the interface in tensile testing. No such voids were observed in the modified lap welds, and fracture occurred through Cu. Thus, as in the case of Al-to-Mg lap FSW recently studied by the authors, modified lap FSW significantly improved the weld quality in Al-to-Cu lap FSW. At the relatively high travel speed of 203 mm/min (8 ipm), however, modified lap FSW was no longer superior because of channel formation.

  14. Surface hardening of two cast irons by friction stir processing

    NASA Astrophysics Data System (ADS)

    Fujii, Hidetoshi; Yamaguchi, Yasufumi; Kikuchi, Toshifumi; Kiguchi, Shoji; Nogi, Kiyoshi

    2009-05-01

    The Friction Stir Processing (FSP) was applied to the surface hardening of cast irons. Flake graphite cast iron (FC300) and nodular graphite cast iron (FCD700) were used to investigate the validity of this method. The matrices of the FC300 and FC700 cast irons are pearlite. The rotary tool is a 25mm diameter cylindrical tool, and the travelling speed was varied between 50 and 150mm/min in order to control the heat input at the constant rotation speed of 900rpm. As a result, it has been clarified that a Vickers hardness of about 700HV is obtained for both cast irons. It is considered that a very fine martensite structure is formed because the FSP generates the heat very locally, and a very high cooling rate is constantly obtained. When a tool without an umbo (probe) is used, the domain in which graphite is crushed and striated is minimized. This leads to obtaining a much harder sample. The hardness change depends on the size of the martensite, which can be controlled by the process conditions, such as the tool traveling speed and the load. Based on these results, it was clarified that the FSP has many advantages for cast irons, such as a higher hardness and lower distortion. As a result, no post surface heat treatment and no post machining are required to obtain the required hardness, while these processes are generally required when using the traditional methods.

  15. Benefits of the stirred, autorefrigerated reactor in sulfuric acid alkylation

    SciTech Connect

    Ackerman, S.; Lerner, H.; Zaczepinski, S.

    1996-12-01

    Alkylation is a process which combines propylenes, butylenes, and pentylenes with isobutane in the presence of an acid catalyst (H{sub 2}SO{sub 4} or HF) to produce a premium quality gasoline blendstock. The alkylation process was developed in the late 1930`s and processing capacity grew tremendously during World War II in response to demand for aviation gasoline. Since that time, alkylation capacity has steadily grown to supply an important motor gasoline component. Now, more than 50 years later, alkylation is in the spotlight again for reformulated gasoline. Alkylate is a high octane, low sensitivity, low RVP, totally paraffinic material which represents the ideal blendstock for modern gasoline manufacture. Two types of modern reactor systems are currently offered for license to the refining industry for sulfuric acid alkylation. These are the stirred, autorefrigerated system offered by Exxon Research and Engineering (ERE) and the indirect, or effluent refrigerated system offered by others. By means of a case study example, this paper discusses the autorefrigerated reaction system and its benefits.

  16. Joining of Dissimilar Metals By Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid

    The use of friction stir welding (FSW) as a new process for joining dissimilar metals has been studied frequently recently. The present study investigated dissimilar-metal FSW between Al and Mg alloys using the widely used alloys 6061 Al and AZ31B Mg. It focused on the issue of how the joint strength is affected by the welding conditions, including the positions of Al and Mg with respect to the welding tool, the tool travel speed and the tool rotation speed. In spite of studies conducted by many other investigators, understanding of this fundamental issue is still rather limited. Unlike those studies, the present study: (1) determined the heat input by torque and temperature measurements during welding and used it to explain the effect of the welding conditions on the joint strength, (2) used color metallography with Al, Mg, Al3Mg2 and Al12Mg17 shown in different colors to clearly revealed the effect of the welding conditions on the formation of intermetallic compounds and material flow, which are affected by the heat input and which in turn affect the joint strength, and (3) determined the windows for selecting the travel and rotation speeds to optimize the joint strength for various material positions. Furthermore, conventional lap FSW was modified and the joint strength and ductility of the resultant welds were both increased significantly. The modified lap FSW was applied subsequently to Al-to-Cu FSW. The intermetallic compounds in Al-Mg and Al-Cu welds were identified.

  17. 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.

  18. 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.

  19. 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.

  20. Expanding the microalgal industry--continuing controversy or compelling case?

    PubMed

    Stephens, Evan; Ross, Ian L; Hankamer, Ben

    2013-06-01

    Herein we examine the potential role that microalgae might play in the approaching challenges of energy and fuel security, and food and water supply. Microalgal production systems remain the subject of controversy however, generally consisting of arguments about the economic and environment sustainability of these systems. We discuss these aspects and draw some parallels with other systems to highlight real advantages and obstacles to expanding the modern microalgal industry. Emerging alternative production models and the relatively early developmental state of the microalgal biofuels industry provide room for extensive innovation that has the potential to bring the technology to a highly productive maturity.