WorldWideScience

Sample records for challenging nuclear structure

  1. Challenges in Nuclear Structure Theory

    CERN Document Server

    Nazarewicz, Witold

    2016-01-01

    The goal of nuclear structure theory is to build a comprehensive microscopic framework in which properties of nuclei and extended nuclear matter, and nuclear reactions and decays can all be consistently described. Due to novel theoretical concepts, breakthroughs in the experimentation with rare isotopes, increased exchange of ideas across different research areas, and the progress in computer technologies and numerical algorithms, nuclear theorists have been quite successful in solving various bits and pieces of the nuclear many-body puzzle and the prospects are exciting. This article contains a brief, personal perspective on the status of the field.

  2. Structural materials for Gen-IV nuclear reactors: Challenges and opportunities

    Science.gov (United States)

    Murty, K. L.; Charit, I.

    2008-12-01

    Generation-IV reactor design concepts envisioned thus far cater toward a common goal of providing safer, longer lasting, proliferation-resistant and economically viable nuclear power plants. The foremost consideration in the successful development and deployment of Gen-IV reactor systems is the performance and reliability issues involving structural materials for both in-core and out-of-core applications. The structural materials need to endure much higher temperatures, higher neutron doses and extremely corrosive environment, which are beyond the experience of the current nuclear power plants. Materials under active consideration for use in different reactor components include various ferritic/martensitic steels, austenitic stainless steels, nickel-base superalloys, ceramics, composites, etc. This paper presents a summary of various Gen-IV reactor concepts, with emphasis on the structural materials issues depending on the specific application areas. This paper also discusses the challenges involved in using the existing materials under both service and off-normal conditions. Tasks become increasingly complex due to the operation of various fundamental phenomena like radiation-induced segregation, radiation-enhanced diffusion, precipitation, interactions between impurity elements and radiation-produced defects, swelling, helium generation and so forth. Further, high temperature capability (e.g. creep properties) of these materials is a critical, performance-limiting factor. It is demonstrated that novel alloy and microstructural design approaches coupled with new materials processing and fabrication techniques may mitigate the challenges, and the optimum system performance may be achieved under much demanding conditions.

  3. Nuclear structure

    CERN Document Server

    Nazarewicz, W

    1999-01-01

    Current developments in nuclear structure are discussed from a theoretical perspective. The studies of the nuclear many-body system provide us with invaluable information about the nature of the nuclear interaction, nucleonic correlations at various energy-distance scales, and the modes of the nucleonic matter.

  4. Nuclear Structure

    Science.gov (United States)

    Gargano, Angela

    2003-04-01

    An account of recent studies in the field of theoretical nuclear structure is reported. These studies concern essentially research activities performed under the Italian project "Fisica Teorica del Nucleo e dei Sistemi a Molti Corpi". Special attention is addressed to results obtained during the last two years as regards the development of new many-body techniques as well as the interpretation of new experimental aspects of nuclear structure.

  5. Nuclear energy safety - new challenges

    Energy Technology Data Exchange (ETDEWEB)

    Rausch, Julio Cezar; Fonseca, Renato Alves da, E-mail: jrausch@cnen.gov.b, E-mail: rfonseca@cnen.gov.b [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Fukushima accident in March this year, the second most serious nuclear accident in the world, put in evidence a discussion that in recent years with the advent of the 'nuclear renaissance' has been relegated in the background: what factors influence the use safe nuclear energy? Organizational precursor, latent errors, reduction in specific areas of competence and maintenance of nuclear programs is a scenario where the guarantee of a sustainable development of nuclear energy becomes a major challenge for society. A deep discussion of factors that influenced the major accidents despite the nuclear industry use of the so-called 'lessons learned' is needed. Major accidents continue to happen if a radical change is not implemented in the focus of safety culture. (author)

  6. Regulatory challenges in the management of aging of structural materials in nuclear power plants; Retos reguladores en la gestion del envejecimiento de los materiales estructurales de centrales nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Castelo, C.; Mendoza, C.; Mas, E.; Conde, J. M.

    2013-07-01

    The article discusses two major pathways by which a regulatory body, and in particular the CSN, may participate in the acquisition of the necessary knowledge on mechanisms of aging of nuclear structural materials: to participate in forums to share operational experience and R and R project, both nationally and internationally. It notes the importance of this participation to carry out its regulatory function based on the knowledge acquired and the unique challenge of transferring that knowledge to rules and guidelines for their application. The article discusses various R and D projects in which the CSN participates directly. It calls for the presence of regulatory bodies in R and D project funded by the EU and the transfer of the results of such projects to codes, standards or guidelines for feasible implementation. (Author)

  7. The Colombian nuclear scenario: Challenges and opportunities

    Science.gov (United States)

    Martinez, Isabel

    2016-07-01

    In Colombia, the absence of nuclear-oriented policies based on technical knowledge, the closing of the Nuclear Affairs Institute (1956-1998), the association of the word "nuclear" with weapons, plus the country's last six decades of internal conflict and narcotraffic have discourage the technical, social and environmental nuclear advance. However, there are technical, social and economic national challenges that could be faced by the present nuclear technical capacities.

  8. Nuclear structure theory

    CERN Document Server

    Irvine, J M

    1972-01-01

    Nuclear Structure Theory provides a guide to nuclear structure theory. The book is comprised of 23 chapters that are organized into four parts; each part covers an aspect of nuclear structure theory. In the first part, the text discusses the experimentally observed phenomena, which nuclear structure theories need to look into and detail the information that supports those theories. The second part of the book deals with the phenomenological nucleon-nucleon potentials derived from phase shift analysis of nucleon-nucleon scattering. Part III talks about the phenomenological parameters used to de

  9. CHALLENGES POSED BY RETIRED RUSSIAN NUCLEAR SUBMARINES

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, Dieter; Kroken, Ingjerd; Latyshev, Eduard; Griffith, Andrew

    2003-02-27

    The purpose of this paper is to provide an overview of the challenges posed by retired Russian nuclear submarines, review current U.S. and International efforts and provide an assessment of the success of these efforts.

  10. Materials challenges for nuclear systems

    Directory of Open Access Journals (Sweden)

    Todd Allen

    2010-12-01

    Full Text Available The safe and economical operation of any nuclear power system relies to a great extent, on the success of the fuel and the materials of construction. During the lifetime of a nuclear power system which currently can be as long as 60 years, the materials are subject to high temperature, a corrosive environment, and damage from high-energy particles released during fission. The fuel which provides the power for the reactor has a much shorter life but is subject to the same types of harsh environments. This article reviews the environments in which fuels and materials from current and proposed nuclear systems operate and then describes how the creation of the Advanced Test Reactor National Scientific User Facility is allowing researchers from across the United States to test their ideas for improved fuels and materials.

  11. Nuclear structure and astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Grawe, H [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany); Langanke, K [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany); MartInez-Pinedo, G [Gesellschaft fuer Schwerionenforschung (GSI), D-64291 Darmstadt (Germany)

    2007-09-15

    The nuclear structure in regions of the Segre chart which are of astrophysical importance is reviewed. The main emphasis is put on those nuclei that are relevant for stellar nucleosynthesis in fusion processes, and in slow neutron capture, both located close to stability, rapid neutron capture close to the neutron dripline and rapid proton capture near the proton dripline. The basic features of modern nuclear structure, their importance and future potential for astrophysics and their level of predictibility are critically discussed. Recent experimental and theoretical results for shell evolution far off the stability line and consequences for weak interaction processes, proton and neutron capture are reviewed.

  12. Nuclear renaissance, the challenge; Renacimiento Nuclear, Los desafios

    Energy Technology Data Exchange (ETDEWEB)

    Carelli, J.; Aycart, J.

    2009-07-01

    The Nuclear Industry has been able to get prepared for the Renaissance by overcoming many different challenges. Most of them related to shortage in capabilities and resources. However, as new builds approach, new challenges appear in the horizon. Now, those are mostly related to the risk management embedded in huge projects like these. This Article provides a vision on how to face those new challenges, so that the industry will not be damaged in its credibility by lack of commitments or failed executions. (Author)

  13. Computational Challenges in Nuclear Weapons Simulation

    Energy Technology Data Exchange (ETDEWEB)

    McMillain, C F; Adams, T F; McCoy, M G; Christensen, R B; Pudliner, B S; Zika, M R; Brantley, P S; Vetter, J S; May, J M

    2003-08-29

    After a decade of experience, the Stockpile Stewardship Program continues to ensure the safety, security and reliability of the nation's nuclear weapons. The Advanced Simulation and Computing (ASCI) program was established to provide leading edge, high-end simulation capabilities needed to meet the program's assessment and certification requirements. The great challenge of this program lies in developing the tools and resources necessary for the complex, highly coupled, multi-physics calculations required to simulate nuclear weapons. This paper describes the hardware and software environment we have applied to fulfill our nuclear weapons responsibilities. It also presents the characteristics of our algorithms and codes, especially as they relate to supercomputing resource capabilities and requirements. It then addresses impediments to the development and application of nuclear weapon simulation software and hardware and concludes with a summary of observations and recommendations on an approach for working with industry and government agencies to address these impediments.

  14. Nuclear Hybrid Energy Systems: Challenges and Opportunities

    Energy Technology Data Exchange (ETDEWEB)

    P. Sabharwall; S.B. Sitton; S.J. Yoon; C. Stoots

    2014-07-01

    With growing demand of energy and costs of the fossil fuels, coupled with the environmental concerns have resulted in an increased interest in alternative energy sources. Nuclear hybrid energy systems (NHES) are being considered which incorporates renewable energy sources such as solar and wind energy combined with nuclear reactor and energy storage to meet the peak hours demand imposed on the grid, along with providing process heat for other potential industrial applications. This concept could potentially satisfy various energy demands and improve reliability, robustness and resilience for the entire system as a whole, along with economic and net efficiency gains. This paper provides a brief understanding of potential NHES system and architecture along with the challenges

  15. Nuclear fuel supply: challenges and opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Lowen, S. [Cameco Corp., Saskatoon, Saskatchewan (Canada)

    2006-07-01

    Prices of uranium, conversion services and enrichment services have all significantly increased in the last few years. These price increases have generally been driven by a tightening in the supply of these products and services, mostly due to long lead times required to bring these products and services to the market. This paper will describe the various steps in the nuclear fuel cycle for natural and enriched uranium fuel, will discuss the development of the front-end fuel cycle for low void reactivity fuel, and will address the challenges faced in the long-term supply of each component, particularly in the light of potential demand increases as a result of a nuclear renaissance. The opportunities for new capacity and uranium production will be outlined and the process required to achieve sufficient new supply will be discussed. (author)

  16. Nuclear structure far from stability

    CERN Document Server

    Vretenar, D

    2005-01-01

    Modern nuclear structure theory is rapidly evolving towards regions of exotic short-lived nuclei far from stability, nuclear astrophysics applications, and bridging the gap between low-energy QCD and the phenomenology of finite nuclei. The principal objective is to build a consistent microscopic theoretical framework that will provide a unified description of bulk properties, nuclear excitations and reactions. Stringent constraints on the microscopic approach to nuclear dynamics, effective nuclear interactions, and nuclear energy density functionals, are obtained from studies of the structure and stability of exotic nuclei with extreme isospin values, as well as extended asymmetric nucleonic matter. Recent theoretical advances in the description of structure phenomena in exotic nuclei far from stability are reviewed.

  17. Nuclear structure far from stability

    Science.gov (United States)

    Vretenar, D.

    2005-04-01

    Modern nuclear structure theory is rapidly evolving towards regions of exotic shortlived nuclei far from stability, nuclear astrophysics applications, and bridging the gap between low-energy QCD and the phenomenology of finite nuclei. The principal objective is to build a consistent microscopic theoretical framework that will provide a unified description of bulk properties, nuclear excitations and reactions. Stringent constraints on the microscopic approach to nuclear dynamics, effective nuclear interactions, and nuclear energy density functionals, are obtained from studies of the structure and stability of exotic nuclei with extreme isospin values, as well as extended asymmetric nucleonic matter. Recent theoretical advances in the description of structure phenomena in exotic nuclei far from stability are reviewed.

  18. Scientific Solutions to Nuclear Waste Environmental Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Bradley R.

    2014-01-30

    The Hidden Cost of Nuclear Weapons The Cold War arms race drove an intense plutonium production program in the U.S. This campaign produced approximately 100 tons of plutonium over 40 years. The epicenter of plutonium production in the United States was the Hanford site, a 586 square mile reservation owned by the Department of Energy and located on the Colombia River in Southeastern Washington. Plutonium synthesis relied on nuclear reactors to convert uranium to plutonium within the reactor fuel rods. After a sufficient amount of conversion occurred, the rods were removed from the reactor and allowed to cool. They were then dissolved in an acid bath and chemically processed to separate and purify plutonium from the rest of the constituents in the used reactor fuel. The acidic waste was then neutralized using sodium hydroxide and the resulting mixture of liquids and precipitates (small insoluble particles) was stored in huge underground waste tanks. The byproducts of the U.S. plutonium production campaign include over 53 million gallons of high-level radioactive waste stored in 177 large underground tanks at Hanford and another 34 million gallons stored at the Savannah River Site in South Carolina. This legacy nuclear waste represents one of the largest environmental clean-up challenges facing the world today. The nuclear waste in the Hanford tanks is a mixture of liquids and precipitates that have settled into sludge. Some of these tanks are now over 60 years old and a small number of them are leaking radioactive waste into the ground and contaminating the environment. The solution to this nuclear waste challenge is to convert the mixture of solids and liquids into a durable material that won't disperse into the environment and create hazards to the biosphere. What makes this difficult is the fact that the radioactive half-lives of some of the radionuclides in the waste are thousands to millions of years long. (The half-life of a radioactive substance is the

  19. Chiral EFT based nuclear forces: Achievements and challenges

    CERN Document Server

    Machleidt, R

    2016-01-01

    During the past two decades, chiral effective field theory has become a popular tool to derive nuclear forces from first principles. Two-nucleon interactions have been worked out up to sixth order of chiral perturbation theory and three-nucleon forces up to fifth order. Applications of some of these forces have been conducted in nuclear few- and many-body systems---with a certain degree of success. But in spite of these achievements, we are still faced with great challenges. Among them is the issue of a proper uncertainty quantification of predictions obtained when applying these forces in {\\it ab initio} calculations of nuclear structure and reactions. A related problem is the order by order convergence of the chiral expansion. We start this review with a pedagogical introduction and then present the current status of the field of chiral nuclear forces. This is followed by a discussion of representative examples for the application of chiral two- and three-body forces in the nuclear many-body system includin...

  20. Symmetries in nuclear structure

    CERN Document Server

    Allaart, K; Dieperink, A

    1983-01-01

    The 1982 summer school on nuclear physics, organized by the Nuclear Physics Division of the Netherlands' Physical Society, was the fifth in a series that started in 1963. The number of students attending has always been about one hundred, coming from about thirty countries. The theme of this year's school was symmetry in nuclear physics. This book covers the material presented by the enthusi­ astic speakers, who were invited to lecture on this subject. We think they have succeeded in presenting us with clear and thorough introductory talks at graduate or higher level. The time schedule of the school and the location allowed the participants to make many informal contacts during many social activities, ranging from billiards to surf board sailing. We hope and expect that the combination of a relaxed atmosphere during part of the time and hard work during most of the time, has furthered the interest in, and understanding of, nuclear physics. The organization of the summer school was made possible by substantia...

  1. Nuclear Quadrupole Moments and Nuclear Shell Structure

    Science.gov (United States)

    Townes, C. H.; Foley, H. M.; Low, W.

    1950-06-23

    Describes a simple model, based on nuclear shell considerations, which leads to the proper behavior of known nuclear quadrupole moments, although predictions of the magnitudes of some quadrupole moments are seriously in error.

  2. Nuclear Structure at the Limits

    Energy Technology Data Exchange (ETDEWEB)

    Nazarewicz, W.

    1998-01-12

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

  3. Nuclear Structure Near the Drip Lines

    Energy Technology Data Exchange (ETDEWEB)

    Nazarewicz, W.

    1998-08-10

    Experiments with beams of unstable nuclei will make it possible to look closely into many aspects of the nuclear many-body problem. Theoretically, exotic nuclei represent a formidable challenge for the nuclear many-body theories and their power to predict nuclear properties in nuclear terra incognita.

  4. Seismological challenges for stellar structure

    CERN Document Server

    Christensen-Dalsgaard, J

    2010-01-01

    Helioseismology has provided very detailed information about the solar interior, and extensive data on a large number of stars, although at less detail, are promised by the ongoing and upcoming asteroseismic projects. In the solar case there remain serious challenges in understanding the inferred solar structure, particularly in the light of the revised determinations of the solar surface composition. Also, a secure understanding of the origins of solar rotation as inferred from helioseismology, both in the radiative interior and in the convection zone, is still missing. In the stellar case challenges are certain to appear as the data allow more detailed inferences of the properties of stellar cores. Large remaining uncertainties in modelling concerns the properties of convective cores and other processes that may cause mixing. As a result of developing asteroseismic signatures addressing these and other issues, we can look forward to a highly challenging, and hence exciting, era of stellar astrophysics.

  5. Electromobility - challenges for structural durability

    Energy Technology Data Exchange (ETDEWEB)

    Hiebl, A.; Krueger, L. [BMW Group, Muenchen (Germany); Martin, D.

    2011-10-15

    In this lecture the challenges of testing the structural durability of electric vehicles are highlighted. The requirements and in particular differences in those for electric vehicles and cars with internal-combustion engines are compared and illustrated. Current experiences with the MINI E and actual BMW hybrid cars are shown. Furthermore, testing concepts for specific electromobility components and their structural integration into the vehicle are explained. Finally an insight into possible future hybrid cars is presented. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Nuclear structure with coherent states

    CERN Document Server

    Raduta, Apolodor Aristotel

    2015-01-01

    This book covers the essential features of a large variety of nuclear structure properties, both collective and microscopic in nature. Most of results are given in an analytical form thus giving deep insight into the relevant phenomena. Using coherent states as variational states, which allows a description in the classical phase space, or provides the generating function for a boson basis, is an efficient tool to account, in a realistic fashion, for many complex properties. A detailed comparison with all existing nuclear structure models provides readers with a proper framework and, at the same time, demonstrates the prospects for new developments. The topics addressed are very much of current concern in the field. The book will appeal to practicing researchers and, due to its self-contained account, can also be successfully read and used by new graduate students.

  7. The Nuclear Education and Staffing Challenge: Rebuilding Critical Skills in Nuclear Science and Technology

    Energy Technology Data Exchange (ETDEWEB)

    Wogman, Ned A.; Bond, Leonard J.; Waltar, Alan E.; Leber, R E.

    2005-01-01

    The United States, the Department of Energy (DOE) and its National Laboratories, including the Pacific Northwest National Laboratory (PNNL), are facing a serious attrition of nuclear scientists and engineers and their capabilities through the effects of aging staff. Within the DOE laboratories, 75% of nuclear personnel will be eligible to retire by 2010. It is expected that there will be a significant loss of senior nuclear science and technology staff at PNNL within five years. PNNL's nuclear legacy is firmly rooted in the DOE Hanford site, the World War II Manhattan Project, and subsequent programs. Historically, PNNL was a laboratory were 70% of its activities were nuclear/radiological, and now just under 50% of its current business science and technology are nuclear and radiologically oriented. Programs in the areas of Nuclear Legacies, Global Security, Nonproliferation, Homeland Security and National Defense, Radiobiology and Nuclear Energy still involve more than 1,000 of the 3,800 current laboratory staff, and these include more than 420 staff who are certified as nuclear/radiological scientists and engineers. This paper presents the current challenges faced by PNNL that require an emerging strategy to solve the nuclear staffing issues through the maintenance and replenishment of the human nuclear capital needed to support PNNL nuclear science and technology programs.

  8. The Nuclear Education and Staffing Challenge: Rebuilding Critical Skills in Nuclear Science and Technology.

    Energy Technology Data Exchange (ETDEWEB)

    Wogman, Ned A.; Bond, Leonard J.; Waltar, Alan E.; Leber, R. E.

    2005-01-01

    The United States, the Department of Energy (DOE) and its National Laboratories, including the Pacific Northwest National Laboratory (PNNL), are facing a serious attrition of nuclear scientists and engineers and their capabilities through the effects of aging staff. Within the DOE laboratories, 75% of nuclear personnel will be eligible to retire by 2010. It is expected that there will be a significant loss of senior nuclear science and technology staff at PNNL within five years. PNNL's nuclear legacy is firmly rooted in the DOE Hanford site, the World War II Manhattan Project, and subsequent programs. Historically, PNNL was a laboratory where 70% of its activities were nuclear/radiological, and now just under 50% of its current business science and technology are nuclear and radiologically oriented. Programs in the areas of Nuclear Legacies, Global Security, Nonproliferation, Homeland Security and National Defense, Radiobiology and Nuclear Energy still involve more than 1,000 of the 3,800 current laboratory staff, and these include more than 420 staff who are certified as nuclear/radiological scientists and engineers. This paper presents the current challenges faced by PNNL that require an emerging strategy to solve the nuclear staffing issues through the maintenance and replenishment of the human nuclear capital needed to support PNNL nuclear science and technology programs.

  9. Theoretical studies in nuclear reactions and nuclear structure. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon`s mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon`s mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon`s mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e{sup +}e{sup {minus}} problem and heavy ion dynamics.

  10. Theoretical studies in nuclear reactions and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    1992-05-01

    Research in the Maryland Nuclear Theory Group focusses on problems in four basic areas of current relevance. Hadrons in nuclear matter; the structure of hadrons; relativistic nuclear physics and heavy ion dynamics and related processes. The section on hadrons in nuclear matter groups together research items which are aimed at exploring ways in which the properties of nucleons and the mesons which play a role in the nuclear force are modified in the nuclear medium. A very interesting result has been the finding that QCD sum rules supply a new insight into the decrease of the nucleon's mass in the nuclear medium. The quark condensate, which characterizes spontaneous chiral symmetry breaking of the late QCD vacuum, decreases in nuclear matter and this is responsible for the decrease of the nucleon's mass. The section on the structure of hadrons contains progress reports on our research aimed at understanding the structure of the nucleon. Widely different approaches are being studied, e.g., lattice gauge calculations, QCD sum rules, quark-meson models with confinement and other hedgehog models. A major goal of this type of research is to develop appropriate links between nuclear physics and QCD. The section on relativistic nuclear physics represents our continuing interest in developing an appropriate relativistic framework for nuclear dynamics. A Lorentz-invariant description of the nuclear force suggests a similar decrease of the nucleon's mass in the nuclear medium as has been found from QCD sum rules. Work in progress extends previous successes in elastic scattering to inelastic scattering of protons by nuclei. The section on heavy ion dynamics and related processes reports on research into the e{sup +}e{sup {minus}} problem and heavy ion dynamics.

  11. Nuclear safety culture in Finland and Sweden - Developments and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Reiman, T.; Pietikaeinen, E. (Technical Research Centre of Finland, VTT (Finland)); Kahlbom, U. (RiskPilot AB (Sweden)); Rollenhagen, C. (Royal Institute of Technology (KTH) (Sweden))

    2011-02-15

    The project aimed at studying the concept of nuclear safety culture and the Nordic nuclear branch safety culture. The project also aimed at looking how the power companies and the regulators view the current responsibilities and role of subcontractors in the Nordic nuclear safety culture as well as to inspect the special demands for safety culture in subcontracting chains. Interview data was collected in Sweden (n = 14) and Finland (n = 16) during 2009. Interviewees represented the major actors in the nuclear field (regulators, power companies, expert organizations, waste management organizations). Results gave insight into the nature and evaluation of safety culture in the nuclear industry. Results illustrated that there is a wide variety of views on matters that are considered important for nuclear safety within the Nordic nuclear community. However, the interviewees considered quite uniformly such psychological states as motivation, mindfulness, sense of control, understanding of hazards and sense of responsibility as important for nuclear safety. Results also gave insight into the characteristics of Nordic nuclear culture. Various differences in safety cultures in Finland and Sweden were uncovered. In addition to the differences, historical reasons for the development of the nuclear safety cultures in Finland and Sweden were pointed out. Finally, results gave implications that on the one hand subcontractors can bring new ideas and improvements to the plants' practices, but on the other hand the assurance of necessary safety attitudes and competence of the subcontracting companies and their employees is considered as a challenge. The report concludes that a good safety culture requires a deep and wide understanding of nuclear safety including the various accident mechanisms of the power plants as well as a willingness to continuously develop one's competence and understanding. An effective and resilient nuclear safety culture has to foster a constant

  12. Fukushima nuclear incident: the challenges of risk communication.

    Science.gov (United States)

    Robertson, Andrew G; Pengilley, Andrew

    2012-07-01

    On March 11, 2011, a magnitude 9.0 earthquake occurred off the Sanriku coast of Japan, which resulted in multiple tsunamis. The earthquake and tsunami damaged several nuclear power stations, with the Fukushima Dai-ichi Nuclear Power Plant being the worst affected, which led Japan to declare a State of Nuclear Emergency. As of November 9, 2011, the National Police Agency of Japan reported a death toll of 15 836 people, with 3664 people still reported missing, following the earthquake and tsunami. Australian radiation health advisers were deployed to Tokyo early in the nuclear emergency to assist the Australian Embassy in assessing the radiological threat, to provide risk advice to Embassy staff and Australian citizens in Japan, and to plan for any further deterioration in the nuclear situation. This article explores the challenges of risk assessment, risk communication, and contingency planning for expatriate staff in the worst nuclear incident since Chernobyl, outlines what measures were successful in addressing heightened perceived risks, and identifies areas where further research is required, particularly in a radiological context.

  13. Structural materials challenges for advanced reactor systems

    Science.gov (United States)

    Yvon, P.; Carré, F.

    2009-03-01

    Key technologies for advanced nuclear systems encompass high temperature structural materials, fast neutron resistant core materials, and specific reactor and power conversion technologies (intermediate heat exchanger, turbo-machinery, high temperature electrolytic or thermo-chemical water splitting processes, etc.). The main requirements for the materials to be used in these reactor systems are dimensional stability under irradiation, whether under stress (irradiation creep or relaxation) or without stress (swelling, growth), an acceptable evolution under ageing of the mechanical properties (tensile strength, ductility, creep resistance, fracture toughness, resilience) and a good behavior in corrosive environments (reactor coolant or process fluid). Other criteria for the materials are their cost to fabricate and to assemble, and their composition could be optimized in order for instance to present low-activation (or rapid desactivation) features which facilitate maintenance and disposal. These requirements have to be met under normal operating conditions, as well as in incidental and accidental conditions. These challenging requirements imply that in most cases, the use of conventional nuclear materials is excluded, even after optimization and a new range of materials has to be developed and qualified for nuclear use. This paper gives a brief overview of various materials that are essential to establish advanced systems feasibility and performance for in pile and out of pile applications, such as ferritic/martensitic steels (9-12% Cr), nickel based alloys (Haynes 230, Inconel 617, etc.), oxide dispersion strengthened ferritic/martensitic steels, and ceramics (SiC, TiC, etc.). This article gives also an insight into the various natures of R&D needed on advanced materials, including fundamental research to investigate basic physical and chemical phenomena occurring in normal and accidental operating conditions, lab-scale tests to characterize candidate materials

  14. The high burn-up structure in nuclear fuel

    Directory of Open Access Journals (Sweden)

    Vincenzo V. Rondinella

    2010-12-01

    Full Text Available During its operating life in the core of a nuclear reactor nuclear fuel is subjected to significant restructuring processes determined by neutron irradiation directly through nuclear reactions and indirectly through the thermo-mechanical conditions established as a consequence of such reactions. In today's light water reactors, starting after ∼4 years of operation the cylindrical UO2 fuel pellet undergoes a transformation that affects its outermost radial region. The discovery of a newly forming structure necessitated the answering of important questions concerning the safety of extended fuel operation and still today poses the fascinating scientific challenge of fully understanding the microstructural mechanisms responsible for its formation.

  15. Teaching nuclear energy: the challenges of interdisciplinarity in the classroom

    Energy Technology Data Exchange (ETDEWEB)

    Bratt, D. [Mount Royal Univ., Dept. of Policy Studies, Calgary, Alberta (Canada); McCollum, B. [Mount Royal Univ. Dept. of Chemical and Biological Sciences, Calgary, Alberta (Canada)

    2012-07-01

    Drs. Bratt and McCollum teach a third year undergraduate course entitled 'The Science and Politics of Nuclear Energy' at Mount Royal University in Calgary. To the best of our knowledge this is the only course of its kind offered in Canada that combines science and politics of nuclear energy in the same course and taught by specialists in both of those areas. The presentation would cover the following key points: Why was the course conceived? What was the role of MRU's focus on General Education? How was the course conceived? What is unique about it? What is the course content? How is the material delivered? What is the student profile? Explaining the success of the course. From Winter 2011 when there were only 5 registered students in a 30 seat course, to 31 registered students in a 30 seat course in Winter 2012. Challenges of a multi-disciplinary course, ie., science students who are afraid of writing long political papers, social science students who are afraid of the periodic table and math. Challenges of teaching such a course in Calgary, ie., lack of a nuclear industry, lack of guest speakers, etc. The methodology for the course includes: Demographic statistics from student enrolments; Content analysis of course documents Instructor's views on the course; and, A student survey.

  16. Global nuclear-structure calculations

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, P.; Nix, J.R.

    1990-04-20

    The revival of interest in nuclear ground-state octupole deformations that occurred in the 1980's was stimulated by observations in 1980 of particularly large deviations between calculated and experimental masses in the Ra region, in a global calculation of nuclear ground-state masses. By minimizing the total potential energy with respect to octupole shape degrees of freedom in addition to {epsilon}{sub 2} and {epsilon}{sub 4} used originally, a vastly improved agreement between calculated and experimental masses was obtained. To study the global behavior and interrelationships between other nuclear properties, we calculate nuclear ground-state masses, spins, pairing gaps and {Beta}-decay and half-lives and compare the results to experimental qualities. The calculations are based on the macroscopic-microscopic approach, with the microscopic contributions calculated in a folded-Yukawa single-particle potential.

  17. Nuclear hormone receptor co-repressors: Structure and function

    OpenAIRE

    2012-01-01

    Co-repressor proteins, such as SMRT and NCoR, mediate the repressive activity of unliganded nuclear receptors and other transcription factors. They appear to act as intrinsically disordered “hub proteins” that integrate the activities of a range of transcription factors with a number of histone modifying enzymes. Although these co-repressor proteins are challenging targets for structural studies due to their largely unstructured character, a number of structures have recently been determined ...

  18. Structural optimization: Challenges and opportunities

    Science.gov (United States)

    Sobieszczanski-Sobieski, J.

    1984-01-01

    A review of developments in structural optimization techniques and their interface with growing computer capabilities is presented. Structural design steps comprise functional definition of an object, an evaluation phase wherein external influences are quantified, selection of the design concept, material, object geometry, and the internal layout, and quantification of the physical characteristics. Optimization of a fully stressed design is facilitated by use of nonlinear mathematical programming which permits automated definition of the physics of a problem. Design iterations terminate when convergence is acquired between mathematical and physical criteria. A constrained minimum algorithm has been formulated using an Augmented Lagrangian approach and a generalized reduced gradient to obtain fast convergence. Various approximation techniques are mentioned. The synergistic application of all the methods surveyed requires multidisciplinary teamwork during a design effort.

  19. Electromagnetic studies of nuclear structure and reactions

    Science.gov (United States)

    Hersman, F. W.; Dawson, J. F.; Heisenberg, J. H.; Calarco, J. R.

    1990-06-01

    This report contains papers on the following topics: giant resonance studies; deep inelastic scattering studies; high resolution nuclear structure work; and relativistic RPA; and field theory in the Schroedinger Representation.

  20. Nuclear effects in the structure functions

    Indian Academy of Sciences (India)

    E Marco; E Oset; S K Singh

    2003-11-01

    By using a relativistic framework and accurate nuclear spectral function the structure functions 2 and 3 of deep inelastic charged lepton and neutrino scattering are calculated in nuclei and results are presented.

  1. Progress on nuclear modifications of structure functions

    CERN Document Server

    Kumano, S

    2016-01-01

    We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrino-oscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function $b_1$ is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact ...

  2. Future nuclear fuel cycles: Prospect and challenges for actinide recycling

    Science.gov (United States)

    Warin, Dominique

    2010-03-01

    The global energy context pleads in favour of a sustainable development of nuclear energy since the demand for energy will likely increase, whereas resources will tend to get scarcer and the prospect of global warming will drive down the consumption of fossil fuel. In this context, nuclear power has the worldwide potential to curtail the dependence on fossil fuels and thereby to reduce the amount of greenhouse gas emissions while promoting energy independence. How we deal with nuclear radioactive waste is crucial in this context. In France, the public's concern regarding the long-term waste management made the French Governments to prepare and pass the 1991 and 2006 Acts, requesting in particular the study of applicable solutions for still minimizing the quantity and the hazardousness of final waste. This necessitates High Active Long Life element (such as the Minor Actinides MA) recycling, since the results of fuel cycle R&D could significantly change the challenges for the storage of nuclear waste. HALL recycling can reduce the heat load and the half-life of most of the waste to be buried to a couple of hundred years, overcoming the concerns of the public related to the long-life of the waste and thus aiding the "burying approach" in securing a "broadly agreed political consensus" of waste disposal in a geological repository. This paper presents an overview of the recent R and D results obtained at the CEA Atalante facility on innovative actinide partitioning hydrometallurgical processes. For americium and curium partitioning, these results concern improvements and possible simplifications of the Diamex-Sanex process, whose technical feasibility was already demonstrated in 2005. Results on the first tests of the Ganex process (grouped actinide separation for homogeneous recycling) are also discussed. In the coming years, next steps will involve both better in-depth understanding of the basis of these actinide partitioning processes and, for the new promising

  3. Forging the Link between Nuclear Reactions and Nuclear Structure

    CERN Document Server

    Dickhoff, W H

    2015-01-01

    A review of the recent applications of the dispersive optical model (DOM) is presented. Emphasis is on the nonlocal implementation of the DOM that is capable of describing ground-state properties accurately when data like the nuclear charge density are available. The DOM, conceived by Claude Mahaux, provides a unified description of both elastic nucleon scattering and structure information related to single-particle properties below the Fermi energy. We have recently introduced a nonlocal dispersive optical potential for both the real and imaginary part. Nonlocal absorptive potentials yield equivalent elastic differential cross sections for ${}^{40}$Ca as compared to local ones but change the $\\ell$-dependent absorption profile suggesting important consequences for the analysis of nuclear reactions. Below the Fermi energy, nonlocality is essential for an accurate representation of particle number and the nuclear charge density. Spectral properties implied by $(e,e'p)$ and $(p,2p)$ reactions are correctly desc...

  4. Clustering aspects in nuclear structure functions

    CERN Document Server

    Hirai, M; Saito, K; Watanabe, T

    2010-01-01

    For understanding an anomalous nuclear effect experimentally observed for the beryllium-9 nucleus at the Thomas Jefferson National Accelerator Facility (JLab), clustering aspects are studied in structure functions of deep inelastic lepton-nucleus scattering by using momentum distributions calculated in antisymmetrized (or fermionic) molecular dynamics (AMD) and also in a simple shell model for comparison. According to the AMD, the Be-9 nucleus consists of two alpha-like clusters with a surrounding neutron. The clustering produces high-momentum components in nuclear wave functions, which affects nuclear modifications of the structure functions. We investigated whether clustering features could appear in the structure function F_2 of Be-9 along with studies for other light nuclei. We found that nuclear modifications of F_2 are similar in both AMD and shell models within our simple convolution description although there are slight differences in Be-9. It indicates that the anomalous Be-9 result should be explain...

  5. Training Solutions to the Global Challenges of a Nuclear Renaissance

    Energy Technology Data Exchange (ETDEWEB)

    Garces, M.; Chan, S.; Leo, C.; Garcia, S.; Vidal, B.

    2010-07-01

    From East Asia to the United States and all over Europe, the nuclear re-birth is generating demands the training simulation vendors had not faced before. Companies involved in the planning, design, construction and operation of new plants increasingly require simulation tools to satisfy very different needs, all of them on a large scale: education and support of inexperienced newcomer staff, human factors analysis and control room design, e-learning, verification and validation of I and C systems or training and licensing of crews before the actual installations are complete. There is a full set of applications already available to the whole industry to satisfy these needs. End-user friendly Thunder Real-Time Executive (T-REX), poised to become the standard simulation platform for U.S. plants, makes it possible to provide full-scope simulator and simulator exercises to students and others on a memory stick or over the internet. AREVA EPR full-scope training simulator, based on the ALICES integrated object-oriented simulation environment, becomes an engineering simulator for the Flamanville 3 plant under construction in Normandy; the same will happen to the Taishan 1 and 2 simulators in Guangdong (China) while UniStar plans to apply this approach to the future EPR's to be built in the United States. SIREP PWR Basic Principle Simulator, with simplified models which can run on an ordinary PC, is used at GDF SUEZ offices in Brussels to implement their Nuclear Trainees Program. EDF Training Department chooses On-line Micro Simulation (MicroSel), which can be managed with Learning Management Systems, for classroom and stand-alone learning of the basic characteristics of French reactors. All these are examples of how extensive R and D and innovation programs implemented by the simulator providers, some of them under way here in Spain, will help to overcome some of the challenges of the current nuclear expansion.

  6. Theoretical nuclear structure. Progress report for 1997

    Energy Technology Data Exchange (ETDEWEB)

    Nazarewicz, W.; Strayer, M.R.

    1997-12-31

    This research effort is directed toward theoretical support and guidance for the fields of radioactive ion beam physics, gamma-ray spectroscopy, and the interface between nuclear structure and nuclear astrophysics. The authors report substantial progress in all these areas. One measure of progress is publications and invited material. The research described here has led to more than 25 papers that are published, accepted, or submitted to refereed journals, and to 25 invited presentations at conferences and workshops.

  7. Creep of Structural Nuclear Composites

    Energy Technology Data Exchange (ETDEWEB)

    Will Windes; R.W. Lloyd

    2005-09-01

    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor (VHTR) design. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. One of the primary degradation mechanisms anticipated for these core components is high temperature thermal and irradiation enhanced creep. As a consequence, high temperature test equipment, testing methodologies, and test samples for very high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Actual testing of both tubular and flat, "dog-bone"-shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures are currently being established from these high temperature mechanical tests.

  8. Nuclear Structure Research at Richmond

    Energy Technology Data Exchange (ETDEWEB)

    Beausang, Cornelius W. [Univ. of Richmond, VA (United States)

    2015-04-30

    The goals for the final year were; (1) to continue ongoing efforts to develop and enhance GRETINA and work towards GRETA; (2) to investigate the structure of non-yrast states in shape transitional Sm and Gd nuclei; (3) to investigate the structure of selected light Cd nuclei; (4) to exploit the surrogate reaction technique to extract (n,f) cross sections for actinide nuclei, particularly the first measurement of the 236Pu and 237Pu(n,f) cross sections.

  9. Nuclear structure of $^{231}$Ac

    CERN Document Server

    Boutami, R; Mach, H; Kurcewicz, W; Fraile, L M; Gulda, K; Aas, A J; García-Raffi, L M; Løvhøiden, G; Martínez, T; Rubio, B; Taín, J L; Tengblad, O

    2008-01-01

    The low-energy structure of 231Ac has been investigated by means of gamma ray spectroscopy following the beta-decay of 231Ra. Multipolarities of 28 transitions have been established by measuring conversion electrons with a mini-orange electron spectrometer. The decay scheme of 231Ra --> 231Ac has been constructed for the first time. The Advanced Time Delayed beta-gamma-gamma(t) method has been used to measure the half-lives of five levels. The moderately fast B(E1) transition rates derived suggest that the octupole effects, albeit weak, are still present in this exotic nucleus.

  10. Tracking patient radiation exposure: challenges to integrating nuclear medicine with other modalities

    Science.gov (United States)

    Mercuri, Mathew; Rehani, Madan M.; Einstein, Andrew J.

    2013-01-01

    The cumulative radiation exposure to the patient from multiple radiological procedures can place some individuals at significantly increased risk for stochastic effects and tissue reactions. Approaches, such as those in the International Atomic Energy Agency’s Smart Card program, have been developed to track cumulative radiation exposures to individuals. These strategies often rely on the availability of structured dose reports, typically found in the DICOM header. Dosimetry information is currently readily available for many individual x-ray based procedures. Nuclear medicine, of which nuclear cardiology constitutes the majority of the radiation burden in the U.S., currently lags behind x-ray based procedures with respect to reporting of radiation dosimetric information. This paper discusses qualitative differences between nuclear medicine and x-ray based procedures, including differences in the radiation source and measurement of its strength, the impact of biokinetics on dosimetry, and the capability of current scanners to record dosimetry information. These differences create challenges in applying monitoring and reporting strategies used in x-ray based procedures to nuclear medicine, and integrating dosimetry information across modalities. A concerted effort by the medical imaging community, dosimetry specialists and manufacturers of imaging equipment is required to develop strategies to improve the reporting of radiation dosimetry data in nuclear medicine. Some ideas on how to address this issue are suggested. PMID:22695788

  11. Progress on nuclear modifications of structure functions

    Directory of Open Access Journals (Sweden)

    Kumano S.

    2016-01-01

    Full Text Available We report progress on nuclear structure functions, especially on their nuclear modifications and a new tensor structure function for the deuteron. To understand nuclear structure functions is an important step toward describing nuclei and QCD matters from low to high densities and from low to high energies in terms of fundamental quark and gluon degrees of freedom beyond conventional hadron and nuclear physics. It is also practically important for understanding new phenomena in high-energy heavy-ion collisions at RHIC and LHC. Furthermore, since systematic errors of current neutrinooscillation experiments are dominated by uncertainties of neutrino-nucleus interactions, such studies are valuable for finding new physics beyond current framework. Next, a new tensor-polarized structure function b1 is discussed for the deuteron. There was a measurement by HERMES; however, its data are inconsistent with the conventional convolution estimate based on the standard deuteron model with D-state admixture. This fact suggests that a new hadronic phenomenon should exist in the tensor-polarized deuteron at high energies, and it will be experimentally investigated at JLab from the end of 2010’s.

  12. Nuclear structures in Tribolium castaneum oocytes.

    Science.gov (United States)

    Bogolyubov, Dmitry S; Batalova, Florina M; Kiselyov, Artyom M; Stepanova, Irina S

    2013-10-01

    The first ultrastructural and immunomorphological characteristics of the karyosphere (karyosome) and extrachromosomal nuclear bodies in the red flour beetle, Tribolium castaneum, are presented. The karyosphere forms early in the diplotene stage of meiotic prophase by the gathering of all oocyte chromosomes in a limited nuclear volume. Using the BrUTP assay, T. castaneum oocyte chromosomes united in the karyosphere maintain their transcriptional activity until the end of oocyte growth. Hyperphosphorylated RNA polymerase II and basal transcription factors (TFIID and TFIIH) were detected in the perichromatin region of the karyosphere. The T. castaneum karyosphere has an extrachromosomal capsule that separates chromosomes from the rest of the nucleoplasm. Certain structural proteins (F-actin, lamin B) were found in the capsule. Unexpectedly, the karyosphere capsule in T. castaneum oocytes was found to be enriched in TMG-capped snRNAs, which suggests that the capsule is not only a structural support for the karyosphere, but may be involved in biogenesis of snRNPs. We also identified the counterparts of 'universal' extrachromosomal nuclear domains, Cajal bodies (CBs) and interchromatin granule clusters (IGCs). Nuclear bodies containing IGC marker protein SC35 display some features unusual for typical IGCs. SC35 domains in T. castaneum oocytes are predominantly fibrillar complex bodies that do not contain trimethyl guanosine (TMG)-capped small nuclear (sn) RNAs. Microinjections of 2'-O-methyl (U)22 probes into the oocytes allowed revealing poly(A)+ RNAs in these nuclear domains. Several proteins related to mRNA export (heterogeneous ribonucleoprotein core protein A1, export adapters Y14 and Aly and export receptor NXF1) were also detected there. We believe that unusual SC35 nuclear domains of T. castaneum oocytes are possibly involved in mRNP but not snRNP biogenesis.

  13. Nuclear Quantum Effects in Water and Aqueous Systems: Experiment, Theory, and Current Challenges.

    Science.gov (United States)

    Ceriotti, Michele; Fang, Wei; Kusalik, Peter G; McKenzie, Ross H; Michaelides, Angelos; Morales, Miguel A; Markland, Thomas E

    2016-07-13

    Nuclear quantum effects influence the structure and dynamics of hydrogen-bonded systems, such as water, which impacts their observed properties with widely varying magnitudes. This review highlights the recent significant developments in the experiment, theory, and simulation of nuclear quantum effects in water. Novel experimental techniques, such as deep inelastic neutron scattering, now provide a detailed view of the role of nuclear quantum effects in water's properties. These have been combined with theoretical developments such as the introduction of the principle of competing quantum effects that allows the subtle interplay of water's quantum effects and their manifestation in experimental observables to be explained. We discuss how this principle has recently been used to explain the apparent dichotomy in water's isotope effects, which can range from very large to almost nonexistent depending on the property and conditions. We then review the latest major developments in simulation algorithms and theory that have enabled the efficient inclusion of nuclear quantum effects in molecular simulations, permitting their combination with on-the-fly evaluation of the potential energy surface using electronic structure theory. Finally, we identify current challenges and future opportunities in this area of research.

  14. Theoretical descriptions of compound-nuclear reactions: open problems & challenges

    CERN Document Server

    Carlson, Brett V; Hussein, Mahir S

    2014-01-01

    Compound-nuclear processes play an important role for nuclear physics applications and are crucial for our understanding of the nuclear many-body problem. Despite intensive interest in this area, some of the available theoretical developments have not yet been fully tested and implemented. We revisit the general theory of compound-nuclear reactions, discuss descriptions of pre-equilibrium reactions, and consider extensions that are needed in order to get cross section information from indirect measurements.

  15. The Eurosafe Forum 2003: Nuclear expertise and challenges of the enlargement of the European Union

    Energy Technology Data Exchange (ETDEWEB)

    Lacronique, Jean-Francois; Repussard, Jacques (eds.) [Institut de Radioprotection et de Surete Nucleaire, IRSN, B.P. 17, F - 92262 Fontenay-aux-Roses Cedex (France); Hahn, Lothar (ed.) [Gesellschaft fuer Anlagen- und Reaktorsicherheit mbH, GRS, Schwertnergasse 1, D - 50667 Koeln (Germany)

    2003-07-01

    EUROSAFE is an international forum for discussions among experts from technical safety organisations, research institutes, safety authorities, utilities, the industry, public authorities and non-governmental organisations concerning the status of and recent achievements in nuclear installation safety, waste management, radiation safety and nuclear material security. The Eurosafe Forum 2003 - the fifth of its kind - was held at the Palais Brongniart in Paris on November 25 and 26, 2003. This year's theme was: 'Nuclear expertise and challenges of the enlargement of the European Union: speakers in the various European countries about the environmental scan before enlargement, development and structuring perspectives within the enlarged Europe'. The event brought together 445 experts and researchers from around the world (including 124 from Germany, 184 from France, 88 from Eastern Europe, as well as representatives from Korea, Japan, the United States, Canada, Cuba, and Armenia. The proceedings of the symposium can now be consulted online. The fifth edition of the forum focused on nuclear expertise and the challenge of EU-enlargement and the latest work carried out by GRS, IRSN and their partners from the European Union, Switzerland and Eastern Europe. Nuclear energy contributes approximately one third of European electricity production. A high level of nuclear safety is a priority for the countries of Europe. The technical safety organisations play an important role in contributing to that objective through appropriate approaches to major safety issues as part of their assessments and research activities. The challenges to nuclear safety are increasingly international. Changes in underlying technologies such as instrumentation and control, the impact of electricity market deregulation, demands for improved safety, the ageing of nuclear facilities, waste management, maintaining and improving scientific and technical knowledge and the need for greater

  16. In situ structural analysis of the human nuclear pore complex.

    Science.gov (United States)

    von Appen, Alexander; Kosinski, Jan; Sparks, Lenore; Ori, Alessandro; DiGuilio, Amanda L; Vollmer, Benjamin; Mackmull, Marie-Therese; Banterle, Niccolo; Parca, Luca; Kastritis, Panagiotis; Buczak, Katarzyna; Mosalaganti, Shyamal; Hagen, Wim; Andres-Pons, Amparo; Lemke, Edward A; Bork, Peer; Antonin, Wolfram; Glavy, Joseph S; Bui, Khanh Huy; Beck, Martin

    2015-10-01

    Nuclear pore complexes are fundamental components of all eukaryotic cells that mediate nucleocytoplasmic exchange. Determining their 110-megadalton structure imposes a formidable challenge and requires in situ structural biology approaches. Of approximately 30 nucleoporins (Nups), 15 are structured and form the Y and inner-ring complexes. These two major scaffolding modules assemble in multiple copies into an eight-fold rotationally symmetric structure that fuses the inner and outer nuclear membranes to form a central channel of ~60 nm in diameter. The scaffold is decorated with transport-channel Nups that often contain phenylalanine-repeat sequences and mediate the interaction with cargo complexes. Although the architectural arrangement of parts of the Y complex has been elucidated, it is unclear how exactly it oligomerizes in situ. Here we combine cryo-electron tomography with mass spectrometry, biochemical analysis, perturbation experiments and structural modelling to generate, to our knowledge, the most comprehensive architectural model of the human nuclear pore complex to date. Our data suggest previously unknown protein interfaces across Y complexes and to inner-ring complex members. We show that the transport-channel Nup358 (also known as Ranbp2) has a previously unanticipated role in Y-complex oligomerization. Our findings blur the established boundaries between scaffold and transport-channel Nups. We conclude that, similar to coated vesicles, several copies of the same structural building block--although compositionally identical--engage in different local sets of interactions and conformations.

  17. Investigation of Nuclear Partonic Structure. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Henry J. [Univ. of California, Berkeley, CA (United States); Engelage, J. M.

    2016-08-30

    Our research program had two primary goals during the period of this grant, to search for new and rare particles produced in high-energy nuclear collisions and to understand the internal structure of nuclear matter. We have developed electronics to pursue these goals at the Relativistic Heavy Ion Collider (RHIC) in the Solenoidal Tracker at RHIC (STAR) experiment and the AnDY experiment. Our results include discovery of the anti-hyper-triton, anti- 3Λ-barH, which opened a new branch on the chart of the nuclides, and the anti-alpha, anti- 4He, the heaviest form of anti-matter yet seen, as well as uncovering hints of gluon saturation in cold nuclear matter and observation of jets in polarized proton-proton collisions that will be used to probe orbital motion inside protons.

  18. Seismic analysis of nuclear power plant structures

    Science.gov (United States)

    Go, J. C.

    1973-01-01

    Primary structures for nuclear power plants are designed to resist expected earthquakes of the site. Two intensities are referred to as Operating Basis Earthquake and Design Basis Earthquake. These structures are required to accommodate these seismic loadings without loss of their functional integrity. Thus, no plastic yield is allowed. The application of NASTRAN in analyzing some of these seismic induced structural dynamic problems is described. NASTRAN, with some modifications, can be used to analyze most structures that are subjected to seismic loads. A brief review of the formulation of seismic-induced structural dynamics is also presented. Two typical structural problems were selected to illustrate the application of the various methods of seismic structural analysis by the NASTRAN system.

  19. Forging the link between nuclear reactions and nuclear structure

    Directory of Open Access Journals (Sweden)

    Dickhoff W. H.

    2016-01-01

    Full Text Available A review of the recent applications of the dispersive optical model (DOM is presented. Emphasis is on the nonlocal implementation of the DOM that is capable of describing ground-state properties accurately when data like the nuclear charge density are available. The present understanding of the role of short- and long-range physics in determining proton properties near the Fermi energy for stable closed-shell nuclei has relied mostly on data from the (e, e′ p reaction. Hadronic tools to extract such spectroscopic information have been hampered by the lack of a consistent reaction description that provides unambiguous and undisputed results. The DOM, conceived by Claude Mahaux, provides a unified description of both elastic nucleon scattering and structure information related to single-particle properties below the Fermi energy. We have recently introduced a nonlocal dispersive optical potential for both the real and imaginary part. Nonlocal absorptive potentials yield equivalent elastic differential cross sections for 40Ca as compared to local ones but change the l-dependent absorption profile suggesting important consequences for the analysis of nuclear reactions. Below the Fermi energy, nonlocality is essential for an accurate representation of particle number and the nuclear charge density. Spectral properties implied by (e, e′ p and (p, 2p reactions are correctly described, including the energy distribution of about 10% high-momentum protons obtained at Jefferson Lab. The nonlocal DOM allows a complete description of experimental data both above (up to 200 MeV and below the Fermi energy in 40Ca. It is further demonstrated that elastic nucleon-nucleus scattering data constrain the spectral strength in the continuum of orbits that are nominally bound in the independent-particle model. Extension of this analysis to 48Ca allows a prediction of the neutron skin of this nucleus that is larger than most predictions made so far.

  20. Forging the link between nuclear reactions and nuclear structure

    Science.gov (United States)

    Dickhoff, W. H.

    2016-06-01

    A review of the recent applications of the dispersive optical model (DOM) is presented. Emphasis is on the nonlocal implementation of the DOM that is capable of describing ground-state properties accurately when data like the nuclear charge density are available. The present understanding of the role of short- and long-range physics in determining proton properties near the Fermi energy for stable closed-shell nuclei has relied mostly on data from the (e, e' p) reaction. Hadronic tools to extract such spectroscopic information have been hampered by the lack of a consistent reaction description that provides unambiguous and undisputed results. The DOM, conceived by Claude Mahaux, provides a unified description of both elastic nucleon scattering and structure information related to single-particle properties below the Fermi energy. We have recently introduced a nonlocal dispersive optical potential for both the real and imaginary part. Nonlocal absorptive potentials yield equivalent elastic differential cross sections for 40Ca as compared to local ones but change the l-dependent absorption profile suggesting important consequences for the analysis of nuclear reactions. Below the Fermi energy, nonlocality is essential for an accurate representation of particle number and the nuclear charge density. Spectral properties implied by (e, e' p) and (p, 2p) reactions are correctly described, including the energy distribution of about 10% high-momentum protons obtained at Jefferson Lab. The nonlocal DOM allows a complete description of experimental data both above (up to 200 MeV) and below the Fermi energy in 40Ca. It is further demonstrated that elastic nucleon-nucleus scattering data constrain the spectral strength in the continuum of orbits that are nominally bound in the independent-particle model. Extension of this analysis to 48Ca allows a prediction of the neutron skin of this nucleus that is larger than most predictions made so far.

  1. 15th National Conference on Nuclear Structure in China

    CERN Document Server

    Wang, Ning; Zhou, Shan-Gui; Nuclear Structure in China 2014; NSC2014

    2016-01-01

    This volume is a collection of the contributions to the 15th National Conference on Nuclear Structure in China (NSC2014), held on October 25-28, 2014 in Guilin, China and hosted by Guangxi Normal University. It provides an important updated resource in the nuclear physics literature for researchers and graduate students studying nuclear structure and related topics. Recent progress made in the study of nuclear spectroscopy of high-spin states, nuclear mass and half-life, nuclear astrophysics, super-heavy nuclei, unstable nuclei, density functional theory, neutron star and symmetry energy, nuclear matter, and nuclear shell model are covered.

  2. Nuclear structure and Indian Clover array

    Indian Academy of Sciences (India)

    H C Jain

    2001-07-01

    A brief description of the nuclear structure studies performed with the 14-UD pelletron at TIFR has been presented. The experimental facilities developed for these studies are described. Some of the interesting results obtained for mass 70 to 80 nuclei are presented. The development of a recoil mass spectrometer and an Indian clover array for the study of high spin states in nuclei near drip lines is discussed.

  3. Avoidable challenges of a nuclear medicine facility in a developing nation.

    Science.gov (United States)

    Adedapo, Kayode Solomon; Onimode, Yetunde Ajoke; Ejeh, John Enyi; Adepoju, Adewale Oluwaseun

    2013-10-01

    The role of nuclear medicine in disease management in a developing nation is as impactful as it is in other regions of the world. However, in the developing world, the practice of nuclear medicine is faced with a myriad of challenges, which can be easily avoided. In this review, we examine the many avoidable challenges to the practice of nuclear medicine in a developing nation. The review is largely based on personal experiences of the authors who are the pioneers and current practitioners of nuclear medicine in a typical developing nation. If the challenges examined in this review are avoided, the practice of nuclear medicine in such a nation will be more effective and practitioners will be more efficient in service delivery. Hence, the huge benefits of nuclear medicine will be made available to patients in such a developing nation.

  4. Opportunities in nuclear structure and reactions

    Science.gov (United States)

    Nunes, Filomena

    2015-10-01

    The last decade has seen important advances in the area of low energy nuclear physics. New measurements have provided crucial insight into the behavior of nuclei at the limits of stability, including the mapping of the neutron dripline up to Oxygen, investigations of unbound nuclear states, and the discovery of new super-heavy elements. In parallel we have seen a revolution in low-energy nuclear theory, moving toward quantified predictability, rooted in the underlying inter-nucleon forces. But the next decade offers even more opportunities with a new generation factory of rare isotopes, and the anticipated developments in high performance computing. The Facility for Rare Isotope Beams coupled with new state-of-the-art detectors will allow us to access a large fraction of the necessary information for the r-process responsible for making at least half of the heavy elements in our universe. FRIB will provide the needed intensities to study global nuclear properties, shell structure, and collective phenomena far from stability. Key measurements are anticipated, at various facilities, which will inform symmetry tests with rare isotopes. We expect to put strict constraints on the equation of state. These and many other opportunities will be highlighted in this overview talk.

  5. Electromagnetic studies of nucleon and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.

    1993-06-01

    Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.

  6. Nuclear Structure Functions from Constituent Quark Model

    CERN Document Server

    Arash, F; Arash, Firooz; Atashbar-Tehrani, Shahin

    1999-01-01

    We have used the notion of the constituent quark model of nucleon, where a constituent quark carries its own internal structure, and applied it to determine nuclear structure functions ratios. It is found that the description of experimental data require the inclusion of strong shadowing effect for $x<0.01$. Using the idea of vector meson dominance model and other ingredients this effect is calculated in the context of the constituent quark model. It is rather striking that the constituent quark model, used here, gives a good account of the data for a wide range of atomic mass number from A=4 to A=204.

  7. Nuclear death: an unprecedented challenge to psychiatry and religion

    Energy Technology Data Exchange (ETDEWEB)

    Frank, J.D.

    1984-11-01

    The growing danger of a nuclear holocaust has intensified two aspects of the human predicament that concern both religion and psychiatry: the inevitability of death and the disastrous consequences of the characteristic termed pride by theologians and narcissism by psychiatrists. For the first time, humans have power to exterminate themselves and death threatens all ages equally. Pride of power causes leaders to exaggerate their ability to control nuclear weapons; moral pride leads to demonizing enemies. The author considers implications for psychiatrists and clergy, with special reference to preventing a nuclear holocaust.

  8. Structured physical examination data: a modeling challenge.

    Science.gov (United States)

    Doupi, P; van Ginneken, A M

    2001-01-01

    The success of systems facilitating collection of structured data by clinicians is largely dependent on the flexibility of the interface. The Open Record for CAre (ORCA) makes use of a generic model to support knowledge-based structured data entry for a variety of medical domains. An endeavor undertaken recently aimed to cover the broader area of Physical Examination by expanding the contents of the knowledge base. The model was found to be adequately expressive for supporting this task. Maintaining the balance between flexibility of the interface and constraints dictated by reliable retrieval, however, proved to be a considerable challenge. In this paper we illustrate through specific examples the effect of this trade off on the modeling process, together with the rationale for the chosen solutions and suggestions for future research focus.

  9. Challenging Minimum Deterrence: Articulating the Contemporary Relevance of Nuclear Weapons

    Science.gov (United States)

    2016-07-13

    The Long Shadow: Nuclear Weapons and Security in 21st Century Asia , ed. Muthiah Alagappa (Stanford, CA: Stanford University Press, 2008), 135, 148...nuclear weapons to the Asia -Pacific region in response to contingencies.44 All of this is en- abled by a diverse set of weapons and delivery systems...policy today, see Keith B. Payne’s The Great American Gamble: Deterrence Theory and Practice from the Cold War to the Twenty-First Century (Fairfax

  10. Structural Biology of Nuclear Auxin Action.

    Science.gov (United States)

    Dinesh, Dhurvas Chandrasekaran; Villalobos, Luz Irina A Calderón; Abel, Steffen

    2016-04-01

    Auxin coordinates plant development largely via hierarchical control of gene expression. During the past decades, the study of early auxin genes paired with the power of Arabidopsis genetics have unraveled key nuclear components and molecular interactions that perceive the hormone and activate primary response genes. Recent research in the realm of structural biology allowed unprecedented insight into: (i) the recognition of auxin-responsive DNA elements by auxin transcription factors; (ii) the inactivation of those auxin response factors by early auxin-inducible repressors; and (iii) the activation of target genes by auxin-triggered repressor degradation. The biophysical studies reviewed here provide an impetus for elucidating the molecular determinants of the intricate interactions between core components of the nuclear auxin response module.

  11. Nuclear power in the 21st century: Challenges and possibilities.

    Science.gov (United States)

    Horvath, Akos; Rachlew, Elisabeth

    2016-01-01

    The current situation and possible future developments for nuclear power--including fission and fusion processes--is presented. The fission nuclear power continues to be an essential part of the low-carbon electricity generation in the world for decades to come. There are breakthrough possibilities in the development of new generation nuclear reactors where the life-time of the nuclear waste can be reduced to some hundreds of years instead of the present time-scales of hundred thousand of years. Research on the fourth generation reactors is needed for the realisation of this development. For the fast nuclear reactors, a substantial research and development effort is required in many fields--from material sciences to safety demonstration--to attain the envisaged goals. Fusion provides a long-term vision for an efficient energy production. The fusion option for a nuclear reactor for efficient production of electricity has been set out in a focussed European programme including the international project of ITER after which a fusion electricity DEMO reactor is envisaged.

  12. Inspection of Nuclear Power Plant Containment Structures

    Energy Technology Data Exchange (ETDEWEB)

    Graves, H.L.; Naus, D.J.; Norris, W.E.

    1998-12-01

    Safety-related nuclear power plant (NPP) structures are designed to withstand loadings from a number of low-probability external and interval events, such as earthquakes, tornadoes, and loss-of-coolant accidents. Loadings incurred during normal plant operation therefore generally are not significant enough to cause appreciable degradation. However, these structures are susceptible to aging by various processes depending on the operating environment and service conditions. The effects of these processes may accumulate within these structures over time to cause failure under design conditions, or lead to costly repair. In the late 1980s and early 1990s several occurrences of degradation of NPP structures were discovered at various facilities (e.g., corrosion of pressure boundary components, freeze- thaw damage of concrete, and larger than anticipated loss of prestressing force). Despite these degradation occurrences and a trend for an increasing rate of occurrence, in-service inspection of the safety-related structures continued to be performed in a somewhat cursory manner. Starting in 1991, the U.S. Nuclear Regulatory Commission (USNRC) published the first of several new requirements to help ensure that adequate in-service inspection of these structures is performed. Current regulatory in-service inspection requirements are reviewed and a summary of degradation experience presented. Nondestructive examination techniques commonly used to inspect the NPP steel and concrete structures to identify and quantify the amount of damage present are reviewed. Finally, areas where nondestructive evaluation techniques require development (i.e., inaccessible portions of the containment pressure boundary, and thick heavily reinforced concrete sections are discussed.

  13. Chiral nucleon-nucleon forces in nuclear structure calculations

    Directory of Open Access Journals (Sweden)

    Coraggio L.

    2016-01-01

    Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.

  14. Nuclear matrix - structure, function and pathogenesis.

    Science.gov (United States)

    Wasąg, Piotr; Lenartowski, Robert

    2016-12-20

    The nuclear matrix (NM), or nuclear skeleton, is the non-chromatin, ribonucleoproteinaceous framework that is resistant to high ionic strength buffers, nonionic detergents, and nucleolytic enzymes. The NM fulfills a structural role in eukaryotic cells and is responsible for maintaining the shape of the nucleus and the spatial organization of chromatin. Moreover, the NM participates in several cellular processes, such as DNA replication/repair, gene expression, RNA transport, cell signaling and differentiation, cell cycle regulation, apoptosis and carcinogenesis. Short nucleotide sequences called scaffold/matrix attachment regions (S/MAR) anchor the chromatin loops to the NM proteins (NMP). The NMP composition is dynamic and depends on the cell type and differentiation stage or metabolic activity. Alterations in the NMP composition affect anchoring of the S/MARs and thus alter gene expression. This review aims to systematize information about the skeletal structure of the nucleus, with particular emphasis on the organization of the NM and its role in selected cellular processes. We also discuss several diseases that are caused by aberrant NM structure or dysfunction of individual NM elements.

  15. Nuclear Data Covariances in the Indian Context - Progress, Challenges, Excitement and Perspectives

    Science.gov (United States)

    Ganesan, S.

    2015-01-01

    We present a brief overview of progress, challenges, excitement and perspectives in developing nuclear data covariances in the Indian context in relation to target accuracies and sensitivity studies that are of great importance to Bhabha's 3-stage nuclear programme for energy and non-energy applications.

  16. Microscopic Approaches to Nuclear Structure: Configuration Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Ormand, W E

    2007-09-21

    The configuration interaction (CI) approach to solving the nuclear many-body problem, also known as the interacting shell model, has proven to be powerful tool in understanding the structure of nuclei. The principal criticism of past applications of the shell model is the reliance on empirical tuning to interaction matrix elements. If an accurate description of nuclei far from the valley of stability, where little or no data is available, a more fundamental approach is needed. This starts with recent ab initio approaches with effective interactions in the no-core shell model (NCSM). Using effective-field theory for guidance, fully ab initio descriptions of nuclei up to {sup 16}O with QCD based NN, NNN, and NNNN interactions will be possible within the next five years. An important task is then to determine how to use these NCSM results to develop effective interactions to describe heavier nuclei without the need to resort to an empirical retuning with every model space. Thus, it is likely that more traditional CI applications utilizing direct diagonalization and more fundamental interactions will be applicable to nuclei with perhaps up to one hundred constituents. But, these direct diagonalization CI applications will always be computationally limited due to the rapid increase in the number of configurations with particle number. Very recently, the shifted-contour method has been applied to the Auxiliary-field Monte Carlo approach to the Shell Model (AFMCSM), and preliminary applications exhibit a remarkable taming of the notorious sign problem. If the mitigation of the sign problem holds true, the AFMCSM will offer a method to compute quantum correlations to mean-field applications for just about all nuclei; giving exact results for CI model spaces that can approach 10{sup 20-25}. In these lectures, I will discuss modern applications of CI to the nuclear many-body problem that have the potential to guide nuclear structure theory into the next decade.

  17. Update on nuclear structure effects in light muonic atoms

    Science.gov (United States)

    Hernandez, Oscar Javier; Dinur, Nir Nevo; Ji, Chen; Bacca, Sonia; Barnea, Nir

    2016-12-01

    We present calculations of the nuclear structure corrections to the Lamb shift in light muonic atoms, using state-of-the-art nuclear potentials. We outline updated results on finite nucleon size contributions.

  18. Update on nuclear structure effects in light muonic atoms

    CERN Document Server

    Hernandez, Oscar Javier; Ji, Chen; Bacca, Sonia; Barnea, Nir

    2016-01-01

    We present calculations of the nuclear structure corrections to the Lamb shift in light muonic atoms, using state-of-the-art nuclear potentials. We outline updated results on finite nucleon size contributions.

  19. Challenges in describing nuclear reactions outcomes at near-barrier energies

    Science.gov (United States)

    Dasgupta, M.; Simpson, E. C.; Kalkal, S.; Cook, K. J.; Carter, I. P.; Hinde, D. J.; Luong, D. H.

    2017-01-01

    The properties of light nuclei such as 6Li, 7Li, 9Be and 12C, and their reaction outcomes are known to be strongly influenced by their underlying α-cluster structure. Reaction models do not yet exist to allow accurate predictions of outcomes following a collision of these nuclei with another nucleus. As a result, reaction models within GEANT, and nuclear fusion models do not accurately describe measured products or cross sections. Recent measurements at the Australian National University have shown new reaction modes that lead to breakup of 6Li, 7Li into lighter clusters, again presenting a further challenge to current models. The new observations and subsequent model developments will impact on accurate predictions of reaction outcomes of 12C - a three α-cluster nucleus – that is used in heavy ion therapy.

  20. Nuclear power program for Poland: Objectives, framework program and basic challenges

    Energy Technology Data Exchange (ETDEWEB)

    Duda, Miroslaw; Trojanowska, Hanna

    2010-09-15

    On January 13, 2009, Government of Poland adopted a resolution on nuclear power development in Poland and commissioning of the first nuclear power plant in 2020. The decision is in line with the national energy policy aimed at changing the overwhelming domination of coal based power plants which would hinder electricity supply in Poland because of growing ecological requirements, particularly on CO2 emission. The article shows the framework program of nuclear power development with all challenges that Poland will face when changing the historical fuel mix, and after the failure of going nuclear for the first time in 1980s.

  1. The Challenges and Potential of Nuclear Energy for Addressing Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Son H.; Edmonds, James A.

    2007-10-24

    The response to climate change and the stabilization of atmospheric greenhouse gas concentrations has major implications for the global energy system. Stabilization of atmospheric carbon dioxide (CO2) concentrations requires a peak and an indefinite decline of global CO2 emissions. Nuclear energy, along with other technologies, has the potential to contribute to the growing demand for energy without emitting CO2. Nuclear energy is of particular interest because of its global prevalence and its current significant contribution, nearly 20%, to the world’s electricity supply. We have investigated the value of nuclear energy in addressing climate change, and have explored the potential challenges for the rapid and large-scale expansion of nuclear energy as a response to climate change. The scope of this study is long-term and the modeling time frame extends out a century because the nature of nuclear energy and climate change dictate that perspective. Our results indicate that the value of the nuclear technology option for addressing climate change is denominated in trillions of dollars. Several-fold increases to the value of the nuclear option can be expected if there is limited availability of competing carbon-free technologies, particularly fossil-fuel based technologies that can capture and sequester carbon. Challenges for the expanded global use of nuclear energy include the global capacity for nuclear construction, proliferation, uranium availability, and waste disposal. While the economic costs of nuclear fuel and power are important, non-economic issues transcend the issues of costs. In this regard, advanced nuclear technologies and new vision for the global use of nuclear energy are important considerations for the future of nuclear power and climate change.

  2. Institutional Strain and Precarious Values in Meeting Future Nuclear Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Matthews; Todd R. LaPorte

    1998-11-01

    This paper explores the implications of moderately expanding plutonium "pit" production capability within the strongly R&D culture of Los Alamos National Laboratory, especially in terms of the lab's current capacity or "fitness for the future" in which institutional stewardship of the nation's nuclear deterrent capability becomes a primary objective. The institutional properties needed to assure "future fitness" includes the organizational requisites highly reliable operations and sustained institutional constancy in a manner that evokes deep public trust and confidence. Estimates are made of the degree to which the key Division and most relevant Program office in this evolution already exhibits them.

  3. Sustainable urban structures to challenge climate change

    Directory of Open Access Journals (Sweden)

    Emil CREANGA

    2012-07-01

    Full Text Available Public spaces within the city in all their form of different types - streets, boulevards, squares, plazas, market places, green areas - are the backbone of cities. Over the centuries buildings defined the shape and quality of public spaces, valorising them in various ways. The post-modern development of urban form generated a great number of “urban spaces”, where there is no longer correspondence between architectural forms and social and political messages: shopping malls and theme parks, inner public spaces, strip developments etc. Urban sprawl accompanied by loss of agricultural/rural land and its impact on the environment are serious concerns for most cities over Europe. To strike the right balance between inner city regeneration, under-use of urban land in the old abandoned sites and the ecological benefits that accompany the new private business initiatives in suburban areas, is one of the major challenges confronting cities in Europe. The paper will analyze the complex relations between architecture and public space, in an attempt to understand how traditional urban structures, public and green spaces, squares and streets, could provide orientation for quality-oriented regeneration. Case in point is Bucharest - capital city of Romania - where aggressive intervention in the urban structure during the 1980s disrupted the fabric of the city. The investigation is oriented towards fundamental questions such as: how to secure and preserve sites that serve as initial points in upgrading processes, how to balance private investment criteria and the quality interests of the urban communities. The major aim is to provide a support for decision making in restoring the fundamental role of public urban space in shaping urban form and supporting community life.

  4. The TRIUMF nuclear structure program and TIGRESS

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, P.E. [Department of Physics, University of Guelph, Guelph, ON, N1G2W1 (Canada) and TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T2A3 (Canada)]. E-mail: pgarrett@physics.uoguelph.ca; Andreyev, A. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T2A3 (Canada); Simon Frasier University, Burnaby, BC, V5A1S6 (Canada); Austin, R.A.E. [Department of Astronomy and Physics, Saint Mary' s University, Halifax, NS, B3H 3C3 (Canada)] (and others)

    2007-08-15

    The isotope separator and accelerator (ISAC) facility located at the TRIUMF laboratory in Vancouver, Canada, is one of the world's most advanced isotope separator on-line-type radioactive ion beam facilities. An extensive {gamma}-ray spectroscopy programme at ISAC is centred around two major research facilities: (i) the 8{pi} {gamma}-ray spectrometer for {beta}-delayed {gamma}-ray spectroscopy experiments with the low-energy beams from ISAC-I, and (ii) the next generation TRIUMF-ISAC gamma-ray escape suppressed spectrometer (TIGRESS) for in-beam experiments with the accelerated radioactive-ion beams. An overview of these facilities and recent results from the diverse programme of nuclear structure and fundamental interaction studies they support is presented.

  5. Investigations of nuclear structure and nuclear reactions induced by complex projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Sarantites, D.G.

    1990-01-01

    This report discusses research in the following areas: nuclear structure; fusion reactions near and below the barrier; incomplete fusion and fragmentation reactions; and instrumentation and analysis. (LSP).

  6. Two-level convolution formula for nuclear structure function

    Science.gov (United States)

    Ma, Boqiang

    1990-05-01

    A two-level convolution formula for the nuclear structure function is derived in considering the nucleus as a composite system of baryon-mesons which are also composite systems of quark-gluons again. The results show that the European Muon Colaboration effect can not be explained by the nuclear effects as nucleon Fermi motion and nuclear binding contributions.

  7. Key issues in space nuclear power challenges for the future

    Science.gov (United States)

    Brandhorst, Henry W., Jr.

    1991-01-01

    The future appears rich in missions that will extend the frontiers of knowledge, human presence in space, and opportunities for profitable commerce. Key to the success of these ventures is the availability of plentiful, cost effective electric power and assured, low cost access to space. While forecasts of space power needs are problematic, an assessment of future needs based on terrestrial experience has been made. These needs fall into three broad categories: survival, self sufficiency, and industrialization. The cost of delivering payloads to orbital locations from LEO to Mars has been determined and future launch cost reductions projected. From these factors, then, projections of the performance necessary for future solar and nuclear space power options has been made. These goals are largely dependent upon orbital location and energy storage needs. Finally the cost of present space power systems has been determined and projections made for future systems.

  8. Nuclear spectroscopy with Geant4. The superheavy challenge

    Science.gov (United States)

    Sarmiento, Luis G.

    2016-12-01

    The simulation toolkit Geant4 was originally developed at CERN for high-energy physics. Over the years it has been established as a swiss army knife not only in particle physics but it has seen an accelerated expansion towards nuclear physics and more recently to medical imaging and γ- and ion- therapy to mention but a handful of new applications. The validity of Geant4 is vast and large across many particles, ions, materials, and physical processes with typically various different models to choose from. Unfortunately, atomic nuclei with atomic number Z > 100 are not properly supported. This is likely due to the rather novelty of the field, its comparably small user base, and scarce evaluated experimental data. To circumvent this situation different workarounds have been used over the years. In this work the simulation toolkit Geant4 will be introduced with its different components and the effort to bring the software to the heavy and superheavy region will be described.

  9. The international nuclear non-proliferation system: Challenges and choices

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, J.; McGrew, A.G.

    1984-01-01

    When a topic has been under discussion for almost 40 years there is a danger that the literature will become excessively esoteric and that, as Philip Grummett suggests, '...a new scholasticism will arise' (p.79). Originating in a November l982 seminar co-sponsored by the British International Studies Association and the Foreign and Commonwealth Office, this volume is a refreshing, well conceived, and well written antidote to that trend. It is also well timed for the 1985 NPT Review Conference. The eight chapters of the volume are divided into three sections. Following an introduction by Anthony McGrew that touches on all the major themes of the volume, the first section deals with the existing non-proliferation system. In three chapters the historical, institutional and policy-making elements of the present system are outlined. There is a vignette on the Nuclear Suppliers Group in Wilmshurst's chapter one (pp. 28-33). Fischer's informative chapter on the IAEA is followed by Gummett's examination of policy options, including, for example, the linking of conventional weapons transfer to non-proliferation policies. The second section, also of three chapters, examines current issues: the state of the international nuclear industry, and the non-proliferation policies of the United States and Britain. Walker's chapter focuses chiefly on change in the industry-from monopoly to pluralism in suppliers, the effect of the economic recession, and the combined effect of these two factors on international politics. Devine's American non-proliferation chapter is a statement of the State Department view, whilst Keohane's chapter on Britain attempts to put the Trident procurement into a proliferation context. The British chapter is present because of ethnocentric considerations.

  10. Challenges to deployment of twenty-first century nuclear reactor systems

    Science.gov (United States)

    Ion, Sue

    2017-02-01

    The science and engineering of materials have always been fundamental to the success of nuclear power to date. They are also the key to the successful deployment and operation of a new generation of nuclear reactor systems and their associated fuel cycles. This article reflects on some of the historical issues, the challenges still prevalent today and the requirement for significant ongoing materials R&D and discusses the potential role of small modular reactors.

  11. Impact of structural aging on seismic risk assessment of reinforced concrete structures in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Ellingwood, B.; Song, J. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

    1996-03-01

    The Structural Aging Program is addressing the potential for degradation of concrete structural components and systems in nuclear power plants over time due to aging and aggressive environmental stressors. Structures are passive under normal operating conditions but play a key role in mitigating design-basis events, particularly those arising from external challenges such as earthquakes, extreme winds, fires and floods. Structures are plant-specific and unique, often are difficult to inspect, and are virtually impossible to replace. The importance of structural failures in accident mitigation is amplified because such failures may lead to common-cause failures of other components. Structural condition assessment and service life prediction must focus on a few critical components and systems within the plant. Components and systems that are dominant contributors to risk and that require particular attention can be identified through the mathematical formalism of a probabilistic risk assessment, or PRA. To illustrate, the role of structural degradation due to aging on plant risk is examined through the framework of a Level 1 seismic PRA of a nuclear power plant. Plausible mechanisms of structural degradation are found to increase the core damage probability by approximately a factor of two.

  12. Membrane proteins structure and dynamics by nuclear magnetic resonance.

    Science.gov (United States)

    Maltsev, Sergey; Lorigan, Gary A

    2011-10-01

    Membrane proteins represent a challenging class of biological systems to study. They are extremely difficult to crystallize and in most cases they retain their structure and functions only in membrane environments. Therefore, commonly used diffraction methods fail to give detailed molecular structure and other approaches have to be utilized to obtain biologically relevant information. Nuclear magnetic resonance (NMR) spectroscopy, however, can provide powerful structural and dynamical constraints on these complicated systems. Solution- and solid-state NMR are powerful methods for investigating membrane proteins studies. In this work, we briefly review both solution and solid-state NMR techniques for membrane protein studies and illustrate the applications of these methods to elucidate proteins structure, conformation, topology, dynamics, and function. Recent advances in electronics, biological sample preparation, and spectral processing provided opportunities for complex biological systems, such as membrane proteins inside lipid vesicles, to be studied faster and with outstanding quality. New analysis methods therefore have emerged, that benefit from the combination of sample preparation and corresponding specific high-end NMR techniques, which give access to more structural and dynamic information.

  13. Challenges in developing human resources for nuclear safety in South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Tsatsi, Louisa [National Nuclear Regulator, PO BOX 7106, 00046 Centurion (South Africa)

    2008-07-01

    Challenges in developing Human Resources for nuclear safety in South Africa ESKOM Holding Limited which is the South African Government owned utility, operates over 10 power stations. The total installed is about 40 GW, and nuclear contributes only 6 percent. The existing nuclear power station, Koeberg NPP, is comprised of two 900 MW(e) units at the South African west coast near Cape Town. The South African Government has a policy to increase the share of nuclear in the generation mix from 6 percent to 15 percent before the year 2020. The challenge is that there have been a 'greying' of nuclear experts and a shrinking of nuclear engineering and science departments. As a consequence of this, ESKOM has realized that a large number of young engineers and scientists would have to be recruited and then trained in South Africa and abroad. Some people, especially high performers in the industry are continually looking for new challenges and opportunities and though it is important in the nuclear industry to retain these key staff members it have proved to be a serious challenge. The nuclear industry had to consider their national training infrastructures and the South African government in partnership with ESKOM, NECSA and PBMR has started a process of funding university chairs in reactor engineering and allied subjects. These departments undertake research and provide training for the South African nuclear industry. The recruitment process has initially involved the transfer of personnel from ESKOM, NECSA as well as direct recruitment from the market. The primary recruitment process going forward will be from universities and other Further Education Training (FET) institutions with a focus on ESKOM and PBMR providing the specific nuclear training. In this regard, both ESKOM and PBMR provide bursaries, project work and other assistance to selected candidates. Upon completion of studies, the specific training is provided both in-house and with partner national

  14. Nuclear Structure References (NSR) file. [Mostly information for input

    Energy Technology Data Exchange (ETDEWEB)

    Ewbank, W.B.

    1978-08-01

    The use of the Nuclear Structure References file by the Nuclear Data Project at ORNL is described. Much of the report concerns format information of interest only to those preparing input to the system or otherwise needing detailed knowledge of its internal structure. 17 figures. (RWR)

  15. Structural integrity of nuclear reactor pressure vessels

    Science.gov (United States)

    Knott, John F.

    2013-09-01

    The paper starts from concerns expressed by Sir Alan Cottrell, in the early 1970s, related to the safety of the pressurized water reactor (PWR) proposed at that time for the next phase of electrical power generation. It proceeds to describe the design and operation of nuclear generation plant and gives details of the manufacture of PWR reactor pressure vessels (RPVs). Attention is paid to stress-relief cracking and under-clad cracking, experienced with early RPVs, explaining the mechanisms for these forms of cracking and the means taken to avoid them. Particular note is made of the contribution of non-destructive inspection to structural integrity. Factors affecting brittle fracture in RPV steels are described: in particular, effects of neutron irradiation. The use of fracture mechanics to assess defect tolerance is explained, together with the failure assessment diagram embodied in the R6 procedure. There is discussion of the Master Curve and how it incorporates effects of irradiation on fracture toughness. Dangers associated with extrapolation of data to low probabilities are illustrated. The treatment of fatigue-crack growth is described, in the context of transients that may be experienced in the operation of PWR plant. Detailed attention is paid to the thermal shock associated with a large loss-of-coolant accident. The final section reviews the arguments advanced to justify 'Incredibility of Failure' and how these are incorporated in assessments of the integrity of existing plant and proposed 'new build' PWR pressure vessels.

  16. Experimental test of nuclear magnetization distribution and nuclear structure models

    Energy Technology Data Exchange (ETDEWEB)

    Beirsdorfer, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lopez-Urrutia, J Crespo R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Utter, S. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    1999-02-26

    Models exist that ascribe the nuclear magnetic fields to the presence of a single nucleon whose spin is not neutralized by pairing it up with that of another nucleon; other models assume that the generation of the magnetic field is shared among some or all nucleons throughout the nucleus. All models predict the same magnetic field external to the nucleus since this is an anchor provided by experiments. The models differ, however, in their predictions of the magnetic field arrangement within the nucleus for which no data exist. The only way to distinguish which model gives the correct description of the nucleus would be to use a probe inserted into the nucleus. The goal of our project was to develop exactly such a probe and to use it to measure fundamental nuclear quantities that have eluded experimental scrutiny. The need for accurately knowing such quantities extends far beyond nuclear physics and has ramifications in parity violation experiments on atomic traps and the testing of the standard model in elementary particle physics. Unlike scattering experiments that employ streams of free particles, our technique to probe the internal magnetic field distribution of the nucleus rests on using a single bound electron. Quantum mechanics shows that an electron in the innermost orbital surrounding the nucleus constantly dives into the nucleus and thus samples the fields that exist inside. This sampling of the nucleus usually results in only minute shifts in the electron' s average orbital, which would be difficult to detect. By studying two particular energy states of the electron, we can, however, dramatically enhance the effects of the distribution of the magnetic fields in the nucleus. In fact about 2% of the energy difference between the two states, dubbed the hyperfine splitting, is determined by the effects related to the distribution of magnetic fields in the nucleus, A precise measurement of this energy difference (better than 0.01%) would then allow us to

  17. Safety-Related Contractor Activities at Nuclear Power Plants. New Challenges for Regulatory Oversight

    Energy Technology Data Exchange (ETDEWEB)

    Chockie, Alan [Chockie Group International, Inc., Seattle, WA (United States)

    2005-09-15

    The use of contractors has been an integral and important part of the design, construction, operation, and maintenance of nuclear power plants. To ensure the safe and efficient completion of contracted tasks, each nuclear plant licensee has developed and refined formal contract management processes to meet their specific needs and plant requirements. Although these contract management processes have proven to be effective tools for the procurement of support and components tailored to the needs of nuclear power plants, contractor-related incidents and accidents have revealed some serious weaknesses with the implementation of these processes. Identifying and addressing implementation problems are becoming more complicated due to organizational and personnel changes affecting the nuclear power industry. The ability of regulators and licensees to effectively monitor and manage the safety-related performance of contractors will likely be affected by forthcoming organization and personnel changes due to: the aging of the workforce; the decline of the nuclear industry; and the deregulation of nuclear power. The objective of this report is to provide a review of current and potential future challenges facing safety-related contractor activities at nuclear power plants. The purpose is to assist SKI in establishing a strategy for the proactive oversight of contractor safety-related activities at Swedish nuclear power plants and facilities. The nature and role of contractors at nuclear plants is briefly reviewed in the first section of the report. The second section describes the essential elements of the contract management process. Although organizations have had decades of experience with the a contract management process, there remain a number of common implantation weaknesses that have lead to serious contractor-related incidents and accidents. These implementation weaknesses are summarized in the third section. The fourth section of the report highlights the

  18. Relativistic density functional for nuclear structure

    CERN Document Server

    2016-01-01

    This book aims to provide a detailed introduction to the state-of-the-art covariant density functional theory, which follows the Lorentz invariance from the very beginning and is able to describe nuclear many-body quantum systems microscopically and self-consistently. Covariant density functional theory was introduced in nuclear physics in the 1970s and has since been developed and used to describe the diversity of nuclear properties and phenomena with great success. In order to provide an advanced and updated textbook of covariant density functional theory for graduate students and nuclear physics researchers, this book summarizes the enormous amount of material that has accumulated in the field of covariant density functional theory over the last few decades as well as the latest developments in this area. Moreover, the book contains enough details for readers to follow the formalism and theoretical results, and provides exhaustive references to explore the research literature.

  19. Nuclear weapons, scientists, and the post-Cold War challenge selected papers on arms control

    CERN Document Server

    Drell, Sidney D

    2007-01-01

    This volume includes a representative selection of Sidney Drell's recent writings and speeches (circa 1993 to the present) on public policy issues with substantial scientific components. Most of the writings deal with national security, nuclear weapons, and arms control and reflect the author's personal involvement in such issues dating back to 1960. Fifteen years after the demise of the Soviet Union, the gravest danger presented by nuclear weapons is the spread of advanced technology that may result in the proliferation of nuclear weapons. Of most concern would be their acquisition by hostile governments and terrorists who are unconstrained by accepted norms of civilized behavior. The current challenges are to prevent this from happening and, at the same time, to pursue aggressively the opportunity to escape from an outdated nuclear deterrence trap.

  20. Challenges and Opportunities in Nuclear Science and Radiochemistry Education at the University of Missouri

    Science.gov (United States)

    Robertson, J. David; Etter, Randy L.; Miller, William H.; Neumeyer, Gayla M.

    2009-08-01

    Over the last thirty years, numerous reports and workshops have documented the decline in nuclear and radiochemistry education programs in the United States. Practitioners and stakeholders are keenly aware of the impact this decline will have on emerging technologies and critical research and are fully committed to rebuilding programs in nuclear and radiochemistry. The challenge is, however, to persuade our academic peers and administrations to invest in nuclear and radiochemistry education and training programs in view of multiple competing priorities. This paper provides an overview of the expansion of the radiochemistry program and the creation of the Nuclear Energy Technology Workforce (NETWork) Center at the University of Missouri, Columbia and the lessons learned along the way.

  1. High resolution inelastic electron scattering and nuclear structure

    Science.gov (United States)

    Blok, H. B.; Heisenberg, J. H.

    Thanks to the improved characteristics of the experimental set-up electron scattering has become an excellent tool to study the structure of the nucleus. After describing globally how the nuclear structure enters in the formalism of (e,e') reactions and how the high experimental resolution is obtained, several examples of the use of electron scattering for the study of specific nuclear structure questions are discussed.

  2. Future challenges for nuclear power plant development research, and for radiological protection sciences.

    Science.gov (United States)

    Lazo, Edward

    2007-11-01

    The promise of the future shines brightly for nuclear energy technology and production, yet also holds many challenges. Focus on new reactor designs is currently aiming at what is termed the fourth generation of reactors, which will come into operation after 2030. The 10 countries participating in the Generation-IV International Forum to develop the new generation of reactors have designated six reactor designs that will be studied. This paper will briefly discuss some of these challenges in new reactor designs in general. In addition to the challenges posed by new reactor designs, radiation protection is also faced with a series of challenges for the future. These are borne from experience with the implementation of the current system of radiological protection, from the evolution of radiation biological research, and from changes in society in the area of radiological risk assessment and management. This paper will address all of these emerging challenges, and point towards approaches to resolve them in the future.

  3. Challenges in education and qualification of human resources for next nuclear generation

    Energy Technology Data Exchange (ETDEWEB)

    Pupak, Marcia Orrico [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: mopupak@ipen.br

    2009-07-01

    The general goal of this paper is to present an overview of Higher Education and personnel qualification for Nuclear Field by the perspective of the International Atomic Energy Agency (IAEA), also by the Organization for Economic Co-operation and Development (OECD and by the United Nations Educational Scientific and Cultural Organization (UNESCO). On the other hand to present the challenge of the Brazilian Government in redesigning, since 2003, the role of the state in order to make it active for younger generations, while promoting growth and social justice, has guided in all actions carried out under the Policy of Human Resources Management of public personnel. The government should be able to formulate and implement public policies and decide among various options, what is the most appropriate for its Human Resources. For this, they require the strengthening of strategic intelligence and government adoption of new ways of interaction and participation. The role played by the Brazilian Nuclear Energy Commission (CNEN) in looking forward to replace and qualify its nuclear staff, as soon as up, since that the qualification of a human resource in this field demands more than one decade. Last but not least the proactive work of IPEN-CNEN/SP to encourage young generation to enter nuclear area, and the efforts of the Brazilian government to implement an integrated Nuclear Programme to form human resources, to attract and retain students in nuclear engineering and related specialized fields, and how this problem should attract the attention of the entire nuclear community, government and industry. (author)

  4. Scientific Grand Challenges: Forefront Questions in Nuclear Science and the Role of High Performance Computing

    Energy Technology Data Exchange (ETDEWEB)

    Khaleel, Mohammad A.

    2009-10-01

    This report is an account of the deliberations and conclusions of the workshop on "Forefront Questions in Nuclear Science and the Role of High Performance Computing" held January 26-28, 2009, co-sponsored by the U.S. Department of Energy (DOE) Office of Nuclear Physics (ONP) and the DOE Office of Advanced Scientific Computing (ASCR). Representatives from the national and international nuclear physics communities, as well as from the high performance computing community, participated. The purpose of this workshop was to 1) identify forefront scientific challenges in nuclear physics and then determine which-if any-of these could be aided by high performance computing at the extreme scale; 2) establish how and why new high performance computing capabilities could address issues at the frontiers of nuclear science; 3) provide nuclear physicists the opportunity to influence the development of high performance computing; and 4) provide the nuclear physics community with plans for development of future high performance computing capability by DOE ASCR.

  5. Three-dimensional structure of low-density nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Minoru, E-mail: okamoto@nucl.ph.tsukuba.ac.jp [Graduate School of Pure and Applied Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Maruyama, Toshiki, E-mail: maruyama.toshiki@jaea.go.jp [Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata Shirane 2-4, Tokai, Ibaraki 319-1195 (Japan); Graduate School of Pure and Applied Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Yabana, Kazuhiro, E-mail: yabana@nucl.ph.tsukuba.ac.jp [Graduate School of Pure and Applied Science, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Center of Computational Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8571 (Japan); Tatsumi, Toshitaka, E-mail: tatsumi@ruby.scphys.kyoto-u.ac.jp [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)

    2012-07-09

    We numerically explore the pasta structures and properties of low-density nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta structures appears as a metastable state at some transient densities. We also discuss the lattice structure of droplets.

  6. Three dimensional structure of low-density nuclear matter

    CERN Document Server

    Okamoto, Minoru; Yabana, Kazuhiro; Tatsumi, Toshitaka

    2011-01-01

    We numerically explore the pasta structures and properties of low-density nuclear matter without any assumption on the geometry. We observe conventional pasta structures, while a mixture of the pasta structures appears as a metastable state at some transient densities. We also discuss the lattice structure of droplets.

  7. Regulation of eukaryotic DNA replication and nuclear structure

    Institute of Scientific and Technical Information of China (English)

    WUJIARUI

    1999-01-01

    In eukaryote,nuclear structure is a key component for the functions of eukaryotic cells.More and more evidences show that the nuclear structure plays important role in regulating DNA replication.The nuclear structure provides a physical barrier for the replication licensing,participates in the decision where DNA replication initiates,and organizes replication proteins as replication factory for DNA replication.Through these works,new concepts on the regulation of DNA replication have emerged,which will be discussed in this minireview.

  8. Challenges in structural approaches to cell modeling.

    Science.gov (United States)

    Im, Wonpil; Liang, Jie; Olson, Arthur; Zhou, Huan-Xiang; Vajda, Sandor; Vakser, Ilya A

    2016-07-31

    Computational modeling is essential for structural characterization of biomolecular mechanisms across the broad spectrum of scales. Adequate understanding of biomolecular mechanisms inherently involves our ability to model them. Structural modeling of individual biomolecules and their interactions has been rapidly progressing. However, in terms of the broader picture, the focus is shifting toward larger systems, up to the level of a cell. Such modeling involves a more dynamic and realistic representation of the interactomes in vivo, in a crowded cellular environment, as well as membranes and membrane proteins, and other cellular components. Structural modeling of a cell complements computational approaches to cellular mechanisms based on differential equations, graph models, and other techniques to model biological networks, imaging data, etc. Structural modeling along with other computational and experimental approaches will provide a fundamental understanding of life at the molecular level and lead to important applications to biology and medicine. A cross section of diverse approaches presented in this review illustrates the developing shift from the structural modeling of individual molecules to that of cell biology. Studies in several related areas are covered: biological networks; automated construction of three-dimensional cell models using experimental data; modeling of protein complexes; prediction of non-specific and transient protein interactions; thermodynamic and kinetic effects of crowding; cellular membrane modeling; and modeling of chromosomes. The review presents an expert opinion on the current state-of-the-art in these various aspects of structural modeling in cellular biology, and the prospects of future developments in this emerging field.

  9. Nuclear structure far off stability -Implications for nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Grawe, H.; Gorska, M. [GSI, Darmstadt (Germany); Blazhev, A. [GSI, Darmstadt (Germany); University of Sofia, Sofia (Bulgaria); Grzywacz, R. [University of Tennessee, Department of Physics and Astronomy, Knoxville, TN (United States); Mach, H. [Uppsala University, ISV, Nykoeping (Sweden); Mukha, I. [GSI, Darmstadt (Germany); RRC Kurchatov Institute, Moscow (Russian Federation); Katholieke Universiteit Leuven, Leuven (Belgium)

    2006-03-15

    The single-particle structure and shell gap of {sup 100}Sn as inferred from previous in-beam {gamma}-ray spectroscopy has been confirmed in recent studies of seniority and spin-gap isomers by {gamma}{gamma}, {beta}{gamma}, {beta}p{gamma}, p{gamma} and 2p{gamma} spectroscopy. The results for {sup 94,} {sup 95}Ag, {sup 98}Cd and its N=50 isotones {sup 96}Pd and {sup 94}Ru stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np-nh excitations, seniority mixing and E2 polarisation of the {sup 100}Sn core. The strong monopole interaction of the {delta}l=0,1 spin/isospin-flip partners {pi}g{sub 9/2}-{nu}g{sub 7/2} along the N=50 isotones and the {pi}f{sub 5/2}- {nu}g{sub 9/2} pair of nucleons along the Z=28 Ni isotopes are decisive for the evolution of the shell structure towards {sup 100}Sn and {sup 78}Ni. It can be traced back to the tensor force in the effective nucleon-nucleon interaction and provides a straightforward explanation for new shells in neutron-rich light nuclei, implying qualitative predictions for new N=32,34 subshells in Ca isotopes, persistence of the {sup 78}Ni proton and neutron shell gaps and non-equivalence of the g{sub 9/2} valence mirror Ni isotopes and N=50 isotones. This is corroborated by recent experimental data on {sup 56,58}Cr and {sup 70-76}Ni. The implication of monopole driven shell evolution for apparent spin-orbit splitting towards N>>Z and structure along the astrophysical r-path between N=50 and N=82 is discussed. (orig.)

  10. Nuclear energy density optimization: Shell structure

    CERN Document Server

    Kortelainen, M; Nazarewicz, W; Olsen, E; Reinhard, P -G; Sarich, J; Schunck, N; Wild, S M; Davesne, D; Erler, J; Pastore, A

    2013-01-01

    Nuclear density functional theory is the only microscopical theory that can be applied throughout the entire nuclear landscape. Its key ingredient is the energy density functional. In this work, we propose a new parameterization UNEDF2 of the local Skyrme energy density functional. The functional optimization is carried out using the POUNDerS optimization algorithm within the framework of the Skyrme Hartree-Fock-Bogoliubov theory. Compared to the previous parameterization UNEDF1, restrictions on the tensor term of the energy density have been lifted, yielding the most general form of the Skyrme energy density functional up to second order in derivatives of the one-body local density. In order to impose constraints on all the parameters of the functional, selected data on single-particle splittings in spherical doubly-magic nuclei have been included into the experimental dataset. The agreement with both bulk and spectroscopic nuclear properties achieved by the resulting UNEDF2 parameterization is comparable wi...

  11. Nuclear "pasta" structures in low-density nuclear matter and neutron star crust

    CERN Document Server

    Okamoto, Minoru; Yabana, Kazuhiro; Tatsumi, Toshitaka

    2013-01-01

    In neutron star crust, non-uniform structure of nuclear matter is expected, which is called the "pasta" structure. From the recent studies of giant flares in magnetars, these structures might be related to some observables and physical quantities of the neutron star crust. To investigate the above quantities, we numerically explore the pasta structures with a fully threedimensional geometry and study the properties of low-density nuclear matter, based on the relativistic mean-field model and the Thomas-Fermi approximation. We observe typical pasta structures for fixed proton number-fraction and two of them for cold catalyzed matter. We also discuss the crystalline configuration of "pasta".

  12. Nuclear effects in the deuteron structure function

    Energy Technology Data Exchange (ETDEWEB)

    Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Sassot, R. (Lab. de Fisica Teorica, Dept. de Fisica, Univ. Nacional de La Plata (Argentina))

    1992-08-06

    An analysis of nuclear effects in the deuteron quark distributions is carried out in connection with the Gottfried sum rule (GSR), the Drell-Yan proton-neutron asymmetry and the Bjorken sum rule (BSR). It is shown that the small amount of nuclear effects necessary to saturate the GSR experimental data modifies the Drell-Yan asymmetry in an entirely different way as an asymmetric sea does. These effects are of little consequence in the convergence of the BSR to the expected value. (orig.).

  13. Progress and Challenges of Neutrino-Nuclear Cross Sections in the GeV Regime

    Science.gov (United States)

    Mahn, Kendall

    2017-01-01

    Interactions of neutrinos and antineutrinos with nuclear material are an essential ingredient in measurements of neutrino oscillation. As future experiments aim at unprecedented precision of the parameters which govern neutrino mixing, neutrino-nuclear interactions have come under intense scrutiny and interest. This talk will describe the needs of future experiments, the unique challenges of neutrino interaction physics and summarize recent results from a suite of experiments worldwide. The speaker would like to acknowledge support by Department of Energy and the Alfred P. Sloan Foundation.

  14. Challenges to a Man-Machine Interface System in Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yeon Sub [KHNP, Daejeon (Korea, Republic of)

    2009-10-15

    When the APR1400 project started nearly 20 years ago, advanced features such as intelligent alarms, computer-based procedures, and soft control technology were introduced. Although some of these technologies had been utilized in fossil plants, APR1400 opened a new horizon in MMIS for nuclear power plants. Currently, however, it appears that further challenges do not exist in the MMIS area. Engineers are simply busy in designing and constructing the next nuclear plant without exploiting the new features of MMIS. This paper explains newly emerging and feasible technology and suggests new ideas for MMIS compared with other industries.

  15. Investigations of nuclear structure and nuclear reactions induced by complex projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Sarantites, D.G.

    1991-01-01

    The research program of our group touches five areas of nuclear physics: (1) Nuclear structure studies at high spin; (2) Studies at the interface between structure and reactions; (3) Production and study of hot nuclei; (4) Incomplete fusion and fragmentation reactions; and (5) Development and use of novel techniques and instrumentation in the above areas of research. The papers from these areas are discussed in this report.

  16. Structural plasticity of the nuclear envelope and the endoplasmic reticulum

    Directory of Open Access Journals (Sweden)

    Sheval E. V.

    2014-09-01

    Full Text Available The nuclear envelope is a double membrane structure, continuous with endoplasmic reticulum, and the morphological organization of both these structures is quite conservative. However, nuclear envelope and endoplasmic reticulum demonstrate distinct structural plasticity, i. e., based on common organization, cells may form various non-canonical membrane structures that are observed only in specialized types of cells or appear in different pathologies. In this review, we will discuss the mechanisms of the biogenesis of such non-canonical structures, and the possible role of this plasticity in the development of pathological processes.

  17. Generalized Nuclear Data: A New Structure (with Supporting Infrastructure) for Handling Nuclear Data

    Energy Technology Data Exchange (ETDEWEB)

    Mattoon, C.M. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA (United States); Beck, B.R.; Patel, N.R.; Summers, N.C.; Hedstrom, G.W. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA (United States); Brown, D.A. [National Nuclear Data Center, Upton NY (United States)

    2012-12-15

    The Evaluated Nuclear Data File (ENDF) format was designed in the 1960s to accommodate neutron reaction data to support nuclear engineering applications in power, national security and criticality safety. Over the years, the scope of the format has been extended to handle many other kinds of data including charged particle, decay, atomic, photo-nuclear and thermal neutron scattering. Although ENDF has wide acceptance and support for many data types, its limited support for correlated particle emission, limited numeric precision, and general lack of extensibility mean that the nuclear data community cannot take advantage of many emerging opportunities. More generally, the ENDF format provides an unfriendly environment that makes it difficult for new data evaluators and users to create and access nuclear data. The Cross Section Evaluation Working Group (CSEWG) has begun the design of a new Generalized Nuclear Data (or 'GND') structure, meant to replace older formats with a hierarchy that mirrors the underlying physics, and is aligned with modern coding and database practices. In support of this new structure, Lawrence Livermore National Laboratory (LLNL) has updated its nuclear data/reactions management package Fudge to handle GND structured nuclear data. Fudge provides tools for converting both the latest ENDF format (ENDF-6) and the LLNL Evaluated Nuclear Data Library (ENDL) format to and from GND, as well as for visualizing, modifying and processing (i.e., converting evaluated nuclear data into a form more suitable to transport codes) GND structured nuclear data. GND defines the structure needed for storing nuclear data evaluations and the type of data that needs to be stored. But unlike ENDF and ENDL, GND does not define how the data are to be stored in a file. Currently, Fudge writes the structured GND data to a file using the eXtensible Markup Language (XML), as it is ASCII based and can be viewed with any text editor. XML is a meta-language, meaning that it

  18. Generalized Nuclear Data: A New Structure (with Supporting Infrastructure) for Handling Nuclear Data

    Science.gov (United States)

    Mattoon, C. M.; Beck, B. R.; Patel, N. R.; Summers, N. C.; Hedstrom, G. W.; Brown, D. A.

    2012-12-01

    The Evaluated Nuclear Data File (ENDF) format was designed in the 1960s to accommodate neutron reaction data to support nuclear engineering applications in power, national security and criticality safety. Over the years, the scope of the format has been extended to handle many other kinds of data including charged particle, decay, atomic, photo-nuclear and thermal neutron scattering. Although ENDF has wide acceptance and support for many data types, its limited support for correlated particle emission, limited numeric precision, and general lack of extensibility mean that the nuclear data community cannot take advantage of many emerging opportunities. More generally, the ENDF format provides an unfriendly environment that makes it difficult for new data evaluators and users to create and access nuclear data. The Cross Section Evaluation Working Group (CSEWG) has begun the design of a new Generalized Nuclear Data (or 'GND') structure, meant to replace older formats with a hierarchy that mirrors the underlying physics, and is aligned with modern coding and database practices. In support of this new structure, Lawrence Livermore National Laboratory (LLNL) has updated its nuclear data/reactions management package Fudge to handle GND structured nuclear data. Fudge provides tools for converting both the latest ENDF format (ENDF-6) and the LLNL Evaluated Nuclear Data Library (ENDL) format to and from GND, as well as for visualizing, modifying and processing (i.e., converting evaluated nuclear data into a form more suitable to transport codes) GND structured nuclear data. GND defines the structure needed for storing nuclear data evaluations and the type of data that needs to be stored. But unlike ENDF and ENDL, GND does not define how the data are to be stored in a file. Currently, Fudge writes the structured GND data to a file using the eXtensible Markup Language (XML), as it is ASCII based and can be viewed with any text editor. XML is a meta-language, meaning that it

  19. International Workshop on Research, Development, and Demonstration to Enhance the Role of Nuclear Energy in Meeting Climate and Energy Challenges

    OpenAIRE

    Anadon, Laura Diaz; Bosetti, Valentina; Bunn, Matthew G.; Catenacci, Michela; Lee, Audrey

    2011-01-01

    Dramatic growth in nuclear energy would be required for nuclear power to provide a significant part of the carbon-free energy the world is likely to need in the 21st century, or a major part in meeting other energy challenges. This would require increased support from governments, utilities, and publics around the world. Achieving that support is likely to require improved economics and major progress toward resolving issues of nuclear safety, proliferation-resistance, and nuclear waste manag...

  20. Bremsstrahlung photons - an ideal tool in nuclear structure and nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Babilon, Mario [Institut fur Kernphysik, Darmstadt (Germany)

    2005-07-01

    Full text of publication follows. Bremsstrahlung photons, produced by decelerating electrons, are a very useful probe to investigate current topics in nuclear structure and nuclear astrophysics. The photon scattering facility of the superconducting electron accelerator S-DALINAC at the Darmstadt University of Technology allows for high resolution Nuclear Resonance Fluorescence (NRF) experiments up to 10 MeV. One current topic of interest in nuclear structure is the investigation of Pygmy Dipole Resonances (PDR), which are located near the particle threshold. Recently, experiments have been carried out on Ca isotopes [1] as well as on several N=82 nuclei [2] in order to understand the structure of the PDR. Moreover, important astrophysical questions can be investigated using real photons (g,n) reaction rates, which play a major role in nucleosynthesis, can be measured at the S-DALINAC by simulating a quasi-stellar photon bath with variable temperature [3,4].

  1. Emergency response to nuclear, biological and chemical incidents:challenges and countermeasures

    Institute of Scientific and Technical Information of China (English)

    Hai-Long Li; Wen-Jun Tang; Ya-Kun Ma; Ji-Min Jia; Rong-Li Dang; Er-Chen Qiu

    2015-01-01

    Given the multiple terrorist attacks that have occurred in recent years in China, medical rescue teams and specialized incident assessment teams have been established by the government; however, medical rescue after nuclear, biological, and chemical incidents remains challenging and is often inefficient. In the present article, problems were analyzed regarding the assessment of responder countermeasures, training of professionals and the management of emergency medical incidents related to nuclear, biological and chemical attacks. Countermeasures, the establishment of response coordination, public education, practical training and exercise, and a professional consultant team or system should be the focus of emergency medical response facilities. Moreover, the government was offered professionals who are involved in managing nuclear, biological and chemical incidents.

  2. Radii and Binding Energies in Oxygen Isotopes: A Challenge for Nuclear Forces.

    Science.gov (United States)

    Lapoux, V; Somà, V; Barbieri, C; Hergert, H; Holt, J D; Stroberg, S R

    2016-07-29

    We present a systematic study of both nuclear radii and binding energies in (even) oxygen isotopes from the valley of stability to the neutron drip line. Both charge and matter radii are compared to state-of-the-art ab initio calculations along with binding energy systematics. Experimental matter radii are obtained through a complete evaluation of the available elastic proton scattering data of oxygen isotopes. We show that, in spite of a good reproduction of binding energies, ab initio calculations with conventional nuclear interactions derived within chiral effective field theory fail to provide a realistic description of charge and matter radii. A novel version of two- and three-nucleon forces leads to considerable improvement of the simultaneous description of the three observables for stable isotopes but shows deficiencies for the most neutron-rich systems. Thus, crucial challenges related to the development of nuclear interactions remain.

  3. Report on aging of nuclear power plant reinforced concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Naus, D.J.; Oland, C.B. [Oak Ridge National Lab., TN (United States); Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

    1996-03-01

    The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

  4. When the weak challenge the strong: the North Korean nuclear crisis

    OpenAIRE

    Cheon, Jaeho

    1996-01-01

    Approved for public release; distribution is unlimited This thesis examines the political behavior of weak states in crises through a detailed case study of the recent North Korean nuclear crisis. In the early 1990s, North Korea initiated a politcal challenge that threatened both U.S. nonproliferaiton and South Korean defense interests. North Korea manipulated the shared risks of the ensuing crisis to achieve political objectives rather than military victory, which was unobtainable due to ...

  5. The nuclear structure and low-energy reactions (NSLER) collaboration

    Science.gov (United States)

    Dean, D. J.; NSLER Collaboration

    2006-09-01

    The long-term vision of the Nuclear Structure and Low-Energy Reactions (NSLER) collaboration is to arrive at a comprehensive and unified description of nuclei and their reactions that is grounded in the interactions between the constituent nucleons. For this purpose, we will develop a universal energy density functional for nuclei and replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that will deliver maximum predictive power with minimal uncertainties that are well quantified. Nuclear structure and reactions play an essential role in the science to be investigated at rare isotope facilities, and in nuclear physics applications to the Science-Based Stockpile Stewardship Program, next-generation reactors, and threat reduction. We anticipate an expansion of the computational techniques and methods we currently employ, and developments of new treatments, to take advantage of petascale architectures and demonstrate the capability of the leadership class machines to deliver new science heretofore impossible.

  6. The nuclear matrix: a structural milieu for genomic function.

    Science.gov (United States)

    Berezney, R; Mortillaro, M J; Ma, H; Wei, X; Samarabandu, J

    1995-01-01

    While significant progress has been made in elucidating molecular properties of specific genes and their regulation, our understanding of how the whole genome is coordinated has lagged behind. To understand how the genome functions as a coordinated whole, we must understand how the nucleus is put together and functions as a whole. An important step in that direction occurred with the isolation and characterization of the nuclear matrix. Aside from the plethora of functional properties associated with these isolated nuclear structures, they have enabled the first direct examination and molecular cloning of specific nuclear matrix proteins. The isolated nuclear matrix can be used for providing an in vitro model for understanding nuclear matrix organization in whole cells. Recent development of high-resolution and three-dimensional approaches for visualizing domains of genomic organization and function in situ has provided corroborative evidence for the nuclear matrix as the site of organization for replication, transcription, and post-transcriptional processing. As more is learned about these in situ functional sites, appropriate experiments could be designed to test molecular mechanisms with the in vitro nuclear matrix systems. This is illustrated in this chapter by the studies of nuclear matrix-associated DNA replication which have evolved from biochemical studies of in vitro nuclear matrix systems toward three-dimensional computer image analysis of replication sites for individual genes.

  7. A New Light Weight Structural Material for Nuclear Structures

    Energy Technology Data Exchange (ETDEWEB)

    Rabiei, Afsaneh [North Carolina State Univ., Raleigh, NC (United States)

    2016-01-14

    Radiation shielding materials are commonly used in nuclear facilities to attenuate the background ionization radiations to a minimum level for creating a safer workplace, meeting regulatory requirements and maintaining high quality performance. The conventional radiation shielding materials have a number of drawbacks: heavy concrete contains a high amount of elements that are not desirable for an effective shielding such as oxygen, silicon, and calcium; a well known limitation of lead is its low machinability and toxicity, which is causing a major environmental concern. Therefore, an effective and environmentally friendly shielding material with increased attenuation and low mass density is desirable. Close-cell composite metal foams (CMFs) and open-cell Al foam with fillers are light-weight candidate materials that we have studied in this project. Close-cell CMFs possess several suitable properties that are unattainable by conventional radiation shielding materials such as low density and high strength for structural applications, high surface area to volume ratio for excellent thermal isolation with an extraordinary energy absorption capability. Open-cell foam is made up of a network of interconnected solid struts, which allows gas or fluid media to pass through it. This unique structure provided a further motive to investigate its application as radiation shields by infiltrating original empty pores with high hydrogen or boron compounds, which are well known for their excellent neutron shielding capability. The resulting open-cell foam with fillers will not only exhibit light weight and high specific surface area, but also possess excellent radiation shielding capability and good processability. In this study, all the foams were investigated for their radiation shielding efficiency in terms of X-ray, gamma ray and neutron. X-ray transmission measurements were carried out on a high-resolution microcomputed tomography (microCT) system. Gamma-emitting sources: 3.0m

  8. Application of Nuclear Magnetic Resonance and Hybrid Methods to Structure Determination of Complex Systems.

    Science.gov (United States)

    Prischi, Filippo; Pastore, Annalisa

    2016-01-01

    The current main challenge of Structural Biology is to undertake the structure determination of increasingly complex systems in the attempt to better understand their biological function. As systems become more challenging, however, there is an increasing demand for the parallel use of more than one independent technique to allow pushing the frontiers of structure determination and, at the same time, obtaining independent structural validation. The combination of different Structural Biology methods has been named hybrid approaches. The aim of this review is to critically discuss the most recent examples and new developments that have allowed structure determination or experimentally-based modelling of various molecular complexes selecting them among those that combine the use of nuclear magnetic resonance and small angle scattering techniques. We provide a selective but focused account of some of the most exciting recent approaches and discuss their possible further developments.

  9. Structuring Cooperative Nuclear RIsk Reduction Initiatives with China.

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, Larry [Stanford Univ., CA (United States); Reinhardt, Jason Christian [Stanford Univ., CA (United States); Hecker, Siegfried [Stanford Univ., CA (United States)

    2017-03-01

    The Stanford Center for International Security and Cooperation engaged several Chinese nuclear organizations in cooperative research that focused on responses to radiological and nuclear terrorism. The objective was to identify joint research initiatives to reduce the global dangers of such threats and to pursue initial technical collaborations in several high priority areas. Initiatives were identified in three primary research areas: 1) detection and interdiction of smuggled nuclear materials; 2) nuclear forensics; and 3) radiological (“dirty bomb”) threats and countermeasures. Initial work emphasized the application of systems and risk analysis tools, which proved effective in structuring the collaborations. The extensive engagements between national security nuclear experts in China and the U.S. during the research strengthened professional relationships between these important communities.

  10. Probing nuclear bubble structure via neutron star asteroseismology

    CERN Document Server

    Sotani, Hajime; Oyamatsu, Kazuhiro

    2016-01-01

    We consider torsional oscillations that are trapped in a layer of spherical-hole (bubble) nuclear structure, which is expected to occur in the deepest region of the inner crust of a neutron star. Because this layer intervenes between the phase of slab nuclei and the outer core of uniform nuclear matter, torsional oscillations in the bubble phase can be excited separately from usual crustal torsional oscillations. We find from eigenmode analyses for various models of the equation of state of uniform nuclear matter that the fundamental frequencies of such oscillations are almost independent of the incompressibility of symmetric nuclear matter, but strongly depend on the slope parameter of the nuclear symmetry energy $L$. Although the frequencies are also sensitive to the entrainment effect, i.e., what portion of nucleons outside bubbles contribute to the oscillations, by having such a portion fixed, we can successfully fit the calculated fundamental frequencies of torsional oscillations in the bubble phase insi...

  11. QCD and a new paradigm for nuclear structure

    Science.gov (United States)

    Thomas, A. W.

    2016-09-01

    We review the reasons why one might choose to seriously re-examine the traditional approach to nuclear theory where nucleons are treated as immutable. This examination leads us to argue that the modification of the structure of the nucleon when immersed in a nuclear medium is fundamental to how atomic nuclei are built. Consistent with this approach we suggest key experiments which should tell us unambiguously whether there is such a change in the structure of a bound nucleon. We also briefly report on extremely promising recent calculations of the structure of nuclei across the periodic table based upon this idea.

  12. PREFACE: Structure of Exotic Nuclei and Nuclear Forces

    Science.gov (United States)

    Honma, Michio; Otsuka, Takaharu; Aoi, Nori

    2006-11-01

    The International Symposium on `Structure of Exotic Nuclei and Nuclear Forces' was held at The Koshiba Hall, University of Tokyo, on 9 - 12 March 2006. This symposium was organized as an activity of the Grant-in-Aid for the specially promoted area `Monte Carlo Shell Model' from the Ministry of Education, Science, Sports and Culture (MEXT) of Japan. The symposium was sponsored by the Center for Nuclear Study (CNS) and by RIKEN. The purpose of the symposium was to discuss theoretical and experimental developments in the study of the structure of exotic nuclei and its relationship with nuclear forces. There has been much progress recently in our understanding of what the structure of exotic nuclei is and how it can be linked to nuclear forces, with emerging intriguing perspectives. The following subjects were covered in this symposium Present status and future of the shell model Effective interaction theories Experimental results and perspectives Few-body methods including ab initio calculations Advancements of mean-fieeld models Transition between shell and cluster structure Nuclear astrophysics and nuclear structure Particle physics and the shell model Emphasis was placed on the interplay between many-body structures and nuclear forces, and on the experimental clarification of these topics. Around 80 participants attended the symposium and we enjoyed 34 excellent and lively invited talks and 26 oral presentations. The organizing committee consisted of B A Brown (MSU), S Fujii (CNS), M Honma (Aizu), T Kajino (NAO), T Mizusaki (Senshu), T Motobayashi (RIKEN), K Muto (TIT), T Otsuka (Chair, Tokyo/CNS/RIKEN), P Ring (TMU), N Shimizu (Scientific Secretary, Tokyo), S Shimoura (CNS), Y Utsuno (Scientific Secretary, JAEA). Finally, we would like to thank all the speakers and the participants as well as the other organizers for their contributions which made the symposium so successful.

  13. Nuclear medium modification of the F2 structure function

    CERN Document Server

    Athar, M Sajjad; Vacas, M J Vicente

    2009-01-01

    We study the nuclear effects in the electromagnetic structure function $F_{2}(x, Q^2)$ in nuclei in the deep inelastic lepton nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. The ratios $R_{F2}^A(x,Q^2)=\\frac{2F_2^A(x,Q^2)}{AF_{2}^{Deut}(x,Q^2)}$ are obtained and compared with the recent JLAB results for light nuclei that show a non trivial A dependence.

  14. Structural integrity of materials in nuclear service: a bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Heddleson, F.A.

    1977-06-07

    This report contains 679 abstracts from the Nuclear Safety Information Center (NSIC) computer file dated 1973 through 1976 covering material properties with respect to structural integrity. All materials important to the nuclear industry (except concrete) are covered for mechanical properties, chemical properties, corrosion, fracture or failure, radiation damage, creep, cracking, and swelling. Keyword, author, and permuted-title indexes are included for the convenience of the user.

  15. The structural basis of nuclear function.

    Science.gov (United States)

    Jackson, D A; Cook, P R

    1995-01-01

    Most models for transcription and replication involve polymerases that track along the template. We review here experiments that suggest an alternative in which polymerization occurs as the template slides past a polymerase fixed to a large structure in the eukaryotic nucleus--a "factory" attached to a nucleoskeleton. This means that higher-order structure dictates how and when DNA is replicated or transcribed.

  16. From nuclear structure to neutron stars

    CERN Document Server

    Gandolfi, Stefano

    2013-01-01

    Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. As a demonstration, we show that the agreement between theoretical calculations of the charge form factor of 12C and the experimental data is excellent. Applying similar methods to isospin-asymmetric systems allows one to describe neutrons confined in an external potential and homogeneous neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

  17. Structural Ceramic Composites for Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    William Windes; P.A. Lessing; Y. Katoh; L. L. Snead; E. Lara-Curzio; J. Klett; C. Henager, Jr.; R. J. Shinavski

    2005-08-01

    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. Initial irradiation stability studies to determine the maximum dose for each composite type have been initiated within the High Flux Isotope Reactor at Oak Ridge National Laboratory. Test samples exposed to 10 dpa irradiation dose have been completed with future samples to dose levels of 20 and 30 dpa scheduled for completion in following years. Mechanical and environmental testing is being conducted concurrently at the Idaho National Laboratory and at Pacific Northwest National Laboratory. High temperature test equipment, testing methodologies, and test samples for high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Specific attention was paid to the architectural fiber preform design as well as the materials used in construction of the composites. Actual testing of both tubular and flat, "dog-bone" shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures will be established from these mechanical and environmental tests. Close collaborations between the U.S. national laboratories and international collaborators (i.e. France and Japan) are being forged to establish both national and international test standards to be used to qualify ceramic composites for nuclear reactor applications.

  18. Nuclear Pore-Like Structures in a Compartmentalized Bacterium

    Science.gov (United States)

    Sagulenko, Evgeny; Green, Kathryn; Yee, Benjamin; Morgan, Garry; Leis, Andrew; Lee, Kuo-Chang; Butler, Margaret K.; Chia, Nicholas; Pham, Uyen Thi Phuong; Lindgreen, Stinus; Catchpole, Ryan; Poole, Anthony M.; Fuerst, John A.

    2017-01-01

    Planctomycetes are distinguished from other Bacteria by compartmentalization of cells via internal membranes, interpretation of which has been subject to recent debate regarding potential relations to Gram-negative cell structure. In our interpretation of the available data, the planctomycete Gemmata obscuriglobus contains a nuclear body compartment, and thus possesses a type of cell organization with parallels to the eukaryote nucleus. Here we show that pore-like structures occur in internal membranes of G.obscuriglobus and that they have elements structurally similar to eukaryote nuclear pores, including a basket, ring-spoke structure, and eight-fold rotational symmetry. Bioinformatic analysis of proteomic data reveals that some of the G. obscuriglobus proteins associated with pore-containing membranes possess structural domains found in eukaryote nuclear pore complexes. Moreover, immunogold labelling demonstrates localization of one such protein, containing a β-propeller domain, specifically to the G. obscuriglobus pore-like structures. Finding bacterial pores within internal cell membranes and with structural similarities to eukaryote nuclear pore complexes raises the dual possibilities of either hitherto undetected homology or stunning evolutionary convergence. PMID:28146565

  19. 3D Structure and Nuclear Targets

    CERN Document Server

    Dupré, R

    2015-01-01

    Recent experimental and theoretical ideas are laying the ground for a new era in the knowledge of the parton structure of nuclei. We report on two promising directions beyond inclusive deep inelastic scattering experiments, aimed at, among other goals, unveiling the three dimensional structure of the bound nucleon. The 3D structure in coordinate space can be accessed through deep exclusive processes, whose non-perturbative content is parametrized in terms of generalized parton distributions. In this way the distribution of partons in the transverse plane will be obtained, providing a pictorial view of the realization of the European Muon Collaboration effect. In particular, we show how, through the generalized parton distribution framework, non nucleonic degrees of freedom in nuclei can be unveiled. Analogously, the momentum space 3D structure can be accessed by studying transverse momentum dependent parton distributions in semi-inclusive deep inelastic scattering processes. The status of measurements is also...

  20. Risks and challenges associated with the design and construction of a nuclear power plant; Control de riesgos y retos asociados al diseno y construccion de una central nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Liebana Martinez, B.; Armas Garcia, A.; Martinez Gozalo, I.

    2011-07-01

    The construction of a nuclear power plant project, considering the period prior to the operation of the plant, requires a very strict risk control to ensure compliance with a series of challenges. The present paper identifying the most important challenges facing the construct ability and license requirements of the process, identifying the interfaces and proposing a methodology of construction to meet the challenge of a construction process in 5 years.

  1. Rapidity Correlation Structure in Nuclear Collisions

    Science.gov (United States)

    Zin, Christopher; Gavin, Sean; Moschelli, George

    2016-09-01

    The forces that drive the nuclear collision system towards local thermal equilibrium leave few observable traces. Heavy ion experiments report a range of features widely attributed to the hydrodynamic flow of a near-equilibrium quark gluon plasma. In particular, measurements of azimuthal anisotropy provide the most comprehensive support for the hydrodynamic description of these systems. In search of the source of this flow, we turned to smaller proton-proton, proton-nucleus and deuterium-nucleus collisions, expecting to find this effect absent. Instead, these collisions show an azimuthal anisotropy that is comparable to the larger ion-ion systems. How can we learn about the mechanisms that give rise to hydrodynamics if every available collision system exhibits flow? We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time τπ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity ν = η / sT . We formulate methods for computing these correlations using second order dissipative hydrodynamics with noise. Current data are consistent with τπ / ν 10 but targeted measurements can improve this precision. NSF PHY-1207687.

  2. Structural Materials for Innovative Nuclear Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yvon, Pascal [Commissariat a l' energie atomique - CEA (France)

    2011-07-01

    This series of slides deal with: the goals for advanced fission reactor systems; the requirements for structural materials; a focus on two important types of materials: ODS and CMC; a focus on materials under irradiation (multiscale modelling, experimental simulation, 'smart' experiments in materials testing reactors); some concluding remarks.

  3. The Structure Inventory of the Nuclear Pore Complex.

    Science.gov (United States)

    Schwartz, Thomas U

    2016-05-22

    The nuclear pore complex (NPC) is the principal gateway for molecular exchange between nucleus and cytoplasm across the nuclear envelope. Due to its sheer size of estimated 50-112MDa and its complex buildup from about 500-1000 individual proteins, it is a difficult object to study for structural biologists. Here, I review the extensive ensemble of high-resolution structures of the building blocks of the NPC. Concurrent with the increase in size and complexity, these latest, large structures and assemblies can now be used as the basis for hybrid approaches, primarily in combination with cryo-electron microscopic analysis, generating the first structure-based assembly models of the NPC. Going forward, the structures will be critically important for a detailed analysis of the NPC, including function, evolution, and assembly.

  4. Dynamical Structure of Nuclear Excitation in Continuum

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chun-Lei; ZHANG Huan-Qiao; ZHANG Xi-Zhen

    2005-01-01

    @@ Dynamical structures of collective excitation in continuum are studied by calculating the isoscalar and isovector strength as well as transition density of nuclei near the drip-line such as 28O and 34Ca. It is found that for some excited states in continuum the proton and neutron transition density calculated from isoscalar and isovector excitation at some given energies may be different, which will affect the calculation of the polarization for nuclei with N ≠ Z.

  5. A-dependence of weak nuclear structure functions

    Energy Technology Data Exchange (ETDEWEB)

    Haider, H.; Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Simo, I. Ruiz [Dipartimento di Fisica, Universitá degli studi di Trento Via Sommarive 14, Povo (Trento) I-38123 (Italy)

    2015-05-15

    Effect of nuclear medium on the weak structure functions F{sub 2}{sup A}(x, Q{sup 2}) and F{sub 3}{sup A}(x, Q{sup 2}) have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, F{sub i}{sup A}/F{sub i}{sup proton} and F{sub i}{sup A}/F{sub i}{sup deuteron}(i=2,3, A={sup 12}C, {sup 16}O, CH and H{sub 2}O) are obtained.

  6. A Structured Career Intervention Program for Academically Challenged Students

    Science.gov (United States)

    Salleh, Amla; Abdullah, Syed Mohamad; Mahmud, Zuria; Ghavifekr, Simin; Ishak, Noriah

    2013-01-01

    A study was carried out to test the effects of a 2-week structured intervention program on academically challenged students' career development. A quasi-experimental study was designed using pre-tests, post-tests, and a control group approach to examine the effects of the intervention program. Data were collected from both the experimental and…

  7. Nuclear structure aspects in A approximately 90

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Constantinescu, G.; Cutoiu, D.; Ivascu, M.; Zamfir, N.V.; Avrigeanu, M.

    1981-01-01

    A systematic review of the experimental studies on some neutron deficient nuclei in the A approximately 90 region performed at the Bucharest FN tandem is presented. After a brief account of the measurements, several transitionality aspects are evidenced, like a change of structure in the odd Sr isotopes from N = 48 to N = 46 and the occurence of decoupled g 9/2 bands. The description of these characteristics is discussed in connection with the triaxial rotor, with the VMI model, as well as the cluster-vibration and the interacting boson-fermion model. A systematics of the B(E2) values for the 8/sub 1//sup +/ state in the N = 46 isotones is also presented. 12 references.

  8. Interacting boson models of nuclear and nucleon structure

    CERN Document Server

    Bijker, R

    1998-01-01

    Interacting boson models provide an elegant and powerful method to describe collective excitations of complex systems by introducing a set of effective degrees of freedom. We review the interacting boson model of nuclear structure and discuss a recent extension to the nucleon and its excited states.

  9. Detailed requirements for a next generation nuclear data structure.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-07-05

    This document attempts to compile the requirements for the top-levels of a hierarchical arrangement of nuclear data such as found in the ENDF format. This set of requirements will be used to guide the development of a new data structure to replace the legacy ENDF format.

  10. Development of deterioration models and tests of structural materials for nuclear containment structures(III)

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Byung Hwan [Seoul National University, Seoul (Korea)

    2002-03-01

    The nuclear containment structures are very important infrastructures which require much cost for construction and maintenance. If these structures lose their functions and do not ensure their safety, great losses of human lives and properties will result. Therefore, the nuclear containment structures should secure appropriate safety and functions during these service lives. The nuclear concrete structures start to experience deterioration due to severe environmental condition, even though the concrete structures exhibit generally superior durability. It is, therefore, necessary to take appropriate actions at each stage of planning, design and construction to secure safety and functionability. Thorough examination of deterioration mechanism and comprehensive tests have been conducted to explore the durability characteristics of nuclear concrete structures. 88 refs., 70 figs., 12 tabs. (Author)

  11. Crystal Structure of the Herpesvirus Nuclear Egress Complex Provides Insights into Inner Nuclear Membrane Remodeling

    Directory of Open Access Journals (Sweden)

    Tzviya Zeev-Ben-Mordehai

    2015-12-01

    Full Text Available Although nucleo-cytoplasmic transport is typically mediated through nuclear pore complexes, herpesvirus capsids exit the nucleus via a unique vesicular pathway. Together, the conserved herpesvirus proteins pUL31 and pUL34 form the heterodimeric nuclear egress complex (NEC, which, in turn, mediates the formation of tight-fitting membrane vesicles around capsids at the inner nuclear membrane. Here, we present the crystal structure of the pseudorabies virus NEC. The structure revealed that a zinc finger motif in pUL31 and an extensive interaction network between the two proteins stabilize the complex. Comprehensive mutational analyses, characterized both in situ and in vitro, indicated that the interaction network is not redundant but rather complementary. Fitting of the NEC crystal structure into the recently determined cryoEM-derived hexagonal lattice, formed in situ by pUL31 and pUL34, provided details on the molecular basis of NEC coat formation and inner nuclear membrane remodeling.

  12. Lung Structure and the Intrinsic Challenges of Gas Exchange.

    Science.gov (United States)

    Hsia, Connie C W; Hyde, Dallas M; Weibel, Ewald R

    2016-03-15

    Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.

  13. Final Technical Report: Investigation of Nuclear Partonic Structure

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Henry J. [Univ. of California, Berkeley, CA (United States)

    2016-08-30

    Our research program had two primary goals during the period of this grant, to search for new and rare particles produced in high-energy nuclear collisions and to understand the internal structure of nuclear matter. We have developed electronics to pursue these goals at the Relativistic Heavy Ion Collider (RHIC) in the Solenoidal Tracker at RHIC (STAR) experiment and the AnDY experiment. Our results include discovery of the anti-hyper-triton, anti- 3Λ-barH, which opened a new branch on the chart of the nuclides, and the anti-alpha, anti- 4He, the heaviest form of anti-matter yet seen, as well as uncovering hints of gluon saturation in cold nuclear matter and observation of jets in polarized proton-proton collisions that will be used to probe orbital motion inside protons.

  14. Some Aspects of Nuclear Structure in Relativistic Approach

    Institute of Scientific and Technical Information of China (English)

    MAZhong-Yu; RONGJian; CAOLi-Gang; CHENBao-Qiu; LIULing

    2004-01-01

    The nucleon effective interaction in the nuclear medium is investigated in the framework of the DiracBrueckner-Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of nucleon self-energy in the DBHF is adopted for asymmetric nuclear matter. The properties of finite nuclei are investigated with the nucleon effective interaction. The agreement with the experimental data is satisfactory. The relativistic microscopic optical potential in asymmetric nuclear matter is investigated in the DBHF approach. The proton scattering from nuclei is calculated and compared with the experimental data. A proper treatment of the resonant continuum for exotic nuclei is studied. The width effect of the resonant continuum on the pairing correlation is discussed. The quasiparticle relativistic random phase approximation based on the relativistic mean-field ground state in the response function formalism is also addressed.

  15. Probing nuclear bubble structure via neutron star asteroseismology

    Science.gov (United States)

    Sotani, Hajime; Iida, Kei; Oyamatsu, Kazuhiro

    2016-10-01

    We consider torsional oscillations that are trapped in a layer of spherical-hole (bubble) nuclear structure, which is expected to occur in the deepest region of the inner crust of a neutron star. Because this layer intervenes between the phase of slab nuclei and the outer core of uniform nuclear matter, torsional oscillations in the bubble phase can be excited separately from usual crustal torsional oscillations. We find from eigenmode analyses for various models of the equation of state of uniform nuclear matter that the fundamental frequencies of such oscillations are almost independent of the incompressibility of symmetric nuclear matter, but strongly depend on the slope parameter of the nuclear symmetry energy L. Although the frequencies are also sensitive to the entrainment effect, i.e., what portion of nucleons outside bubbles contribute to the oscillations, by having such a portion fixed, we can successfully fit the calculated fundamental frequencies of torsional oscillations in the bubble phase inside a star of specific mass and radius as a function of L. By comparing the resultant fitting formula to the frequencies of quasi-periodic oscillations (QPOs) observed from the soft-gamma repeaters, we find that each of the observed low-frequency QPOs can be identified either as a torsional oscillation in the bubble phase or as a usual crustal oscillation, given generally accepted values of L for all the stellar models considered here.

  16. Nonuniform nuclear structures and QPOs in giant flares

    Energy Technology Data Exchange (ETDEWEB)

    Sotani, Hajime [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2012-11-12

    We show that the shear modes in the neutron star crust are quite sensitive to the existence of nonuniform nuclear structures, the so-called 'pasta'. Due to the existence of pasta phase, the frequencies of shear modes are reduced. Since the torsional shear frequencies depend strongly on the structure of pasta phase, through the observations of stellar oscillations, one can probe the pasta structure in the crust. Additionally, considering the effect of pasta phase, we show the possibility to explain all the observed frequencies in the SGR 1806-20 with using only crust torsional oscillations.

  17. The Structural Engineering Challenges Following the Wenchuan Earthquake

    Institute of Scientific and Technical Information of China (English)

    GRUNDY Paul

    2009-01-01

    Ihe 5 · 12 Wenchuan Larthquake presents two challenges-reconstruction of the devastated areas and building adequate seismic resistance into the rest of China. The stages in recovery include structural condition assessment , identification of seismic weaknesses, appreciation of the variable seismicity of PR China, the development of a seismic performance index to aid the decision to relocate, rebuild or retrofit, development and application of the principles of retrofitting which recycles rubble and waste from Wenchuan "5 ? 12" , with an emphasis on integrating masonry construction into seismic resistance. The recovery and resilience achieved through structural engineering must be integrated into a broader community involvement in disaster risk reduction.

  18. Targeting cytokine/chemokine receptors: a challenge for molecular nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Signore, A. [Nuclear Medicine Unit, Department of Clinical Sciences, Policlinico Umberto I, University ' ' La Sapienza' ' , Via del Policlinico 155, 00161 Roma (Italy); Chianelli, M. [Nuclear Medicine, ' ' Regina Apostolorum' ' Hospital, Albano (Roma) (Italy); Bei, R.; Modesti, A. [Department of Experimental Medicine and Biochemical Sciences, University ' ' Tor Vergata' ' , Roma (Italy); Oyen, W. [Department of Nuclear Medicine, University Medical Center, Nijmegen (Netherlands)

    2003-01-01

    Radiolabelled cytokines and chemokines are a group of radiopharmaceuticals that, by highlighting in vivo the binding to specific high-affinity receptors expressed on selected cell populations, allow the molecular and functional characterisation of immune-mediated processes Recently, several authors have described the use of radiolabelled cytokines and chemokines not only for imaging of inflammation and infection, but also as an approach to study in vivo the biology of primary and metastatic cancer cells. The latter avenue of research has been pursued particularly to help oncologists in therapeutic decision making and to follow up the efficacy of new immune therapies. In this paper we describe the characteristics of cytokines and chemokines, focussing on their role as radiopharmaceuticals for the imaging of cancer cells in vivo, a new challenge for molecular nuclear medicine. (orig.)

  19. The nucleolus: a raft adrift in the nuclear sea or the keystone in nuclear structure?

    Science.gov (United States)

    O'Sullivan, Justin M; Pai, Dave A; Cridge, Andrew G; Engelke, David R; Ganley, Austen R D

    2013-06-01

    The nucleolus is a prominent nuclear structure that is the site of ribosomal RNA (rRNA) transcription, and hence ribosome biogenesis. Cellular demand for ribosomes, and hence rRNA, is tightly linked to cell growth and the rRNA makes up the majority of all the RNA within a cell. To fulfill the cellular demand for rRNA, the ribosomal RNA (rDNA) genes are amplified to high copy number and transcribed at very high rates. As such, understanding the rDNA has profound consequences for our comprehension of genome and transcriptional organization in cells. In this review, we address the question of whether the nucleolus is a raft adrift the sea of nuclear DNA, or actively contributes to genome organization. We present evidence supporting the idea that the nucleolus, and the rDNA contained therein, play more roles in the biology of the cell than simply ribosome biogenesis. We propose that the nucleolus and the rDNA are central factors in the spatial organization of the genome, and that rapid alterations in nucleolar structure in response to changing conditions manifest themselves in altered genomic structures that have functional consequences. Finally, we discuss some predictions that result from the nucleolus having a central role in nuclear organization.

  20. R-ratios and moments of nuclear structure functions

    CERN Document Server

    Rinat, A S

    2000-01-01

    We study implications of a model, which links nuclear and nucleon structure functions. Computed Callen-Gross functions $\\kappa^A(x,Q^2)= 2xF_1^A(x,Q^2)/F_2^A(x,Q^2)$ appear for finite $Q^2$ to be close to their asymptotic value 1. Using those $\\kappa$, we compure $R$ ratios for $Q^2\\ge 5 GeV^2$. We review approximate methods in use for the extraction of $R$ from inclusive scattering and ENC data. Further we calcuate ratios of the moments of $F_k$ and find these to describe the data, in particular their $Q^2$ dependence. The above observables, as well as inclusive cross sections, are sensitive tests for the underlying relation between nucleonic and nuclear structure functions. In view of the overall agreement, we speculate that the above relation effectively circumvents a QCD calculation.

  1. EVALUATED NUCLEAR STRUCTURE DATA FILE -- A MANUAL FOR PREPARATION OF DATA SETS.

    Energy Technology Data Exchange (ETDEWEB)

    TULI, J.K.

    2001-02-01

    This manual describes the organization and structure of the Evaluated Nuclear Structure Data File (ENSDF). This computer-based file is maintained by the National Nuclear Data Center (NNDC) at Brookhaven National Laboratory for the international Nuclear Structure and Decay Data Network. For every mass number (presently, A {le} 293), the Evaluated Nuclear Structure Data File (ENSDF) contains evaluated structure information. For masses A {ge} 44, this information is published in the Nuclear Data Sheets; for A < 44, ENSDF is based on compilations published in the journal Nuclear Physics. The information in ENSDF is updated by mass chain or by nuclide with a varying cycle time dependent on the availability of new information.

  2. Online Monitoring of Concrete Structures in Nuclear Power Plants: Interim Report

    Energy Technology Data Exchange (ETDEWEB)

    Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    The existing fleet of nuclear power plants in the United States have initial operating licenses of 40 years, and many of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code-based design margins of safety. Structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. The online monitoring of concrete structures project conducted under the Advanced Instrumentation, Information, and Control Technologies Pathway of the Light Water Reactor Sustainability program at Idaho National Laboratory is seeking to develop and demonstrate capabilities for concrete structures health monitoring. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses activities in this project during October-December, 2014. The most significant activity during this period was the organizing of a two-day workshop on research needs in online monitoring of concrete structures, hosted by Vanderbilt University in November 2014. Thirty invitees from academia, industry and government participated in the workshop. The presentations and discussions at the workshop surveyed current activities related to concrete structures deterioration modeling and monitoring, and identified the challenges, knowledge gaps, and opportunities for advancing the state of the art; these

  3. Space Nuclear Power and Propulsion: Materials Challenges for the 21st Century

    Science.gov (United States)

    Houts, Mike

    2008-01-01

    The current focus of NASA s space fission effort is Fission Surface Power (FSP). FSP systems could be used to provide power anytime, anywhere on the surface of the Moon or Mars. FSP systems could be used at locations away from the lunar poles or in permanently shaded regions, with no performance penalty. A potential reference 40 kWe option has been devised that is cost-competitive with alternatives while providing more power for less mass. The potential reference system is readily extensible for use on Mars. At Mars the system could be capable of operating through global dust storms and providing year-round power at any Martian latitude. To ensure affordability, the potential near-term, 40 kWe reference concept is designed to use only well established materials and fuels. However, if various materials challenges could be overcome, extremely high performance fission systems could be devised. These include high power, low mass fission surface power systems; in-space systems with high specific power; and high performance nuclear thermal propulsion systems. This tutorial will provide a brief overview of space fission systems and will focus on materials challenges that, if overcome, could help enable advanced exploration and utilization of the solar system.

  4. Unified ab initio approaches to nuclear structure and reactions

    CERN Document Server

    Navratil, Petr; Hupin, Guillaume; Romero-Redondo, Carolina; Calci, Angelo

    2016-01-01

    The description of nuclei starting from the constituent nucleons and the realistic interactions among them has been a long-standing goal in nuclear physics. In addition to the complex nature of the nuclear forces, with two-, three- and possibly higher many-nucleon components, one faces the quantum-mechanical many-nucleon problem governed by an interplay between bound and continuum states. In recent years, significant progress has been made in {\\em ab initio} nuclear structure and reaction calculations based on input from QCD-employing Hamiltonians constructed within chiral effective field theory. After a brief overview of the field, we focus on ab initio many-body approaches - built upon the No-Core Shell Model - that are capable of simultaneously describing both bound and scattering nuclear states, and present results for resonances in light nuclei, reactions important for astrophysics and fusion research. In particular, we review recent calculations of resonances in the $^6$He halo nucleus, of five- and six...

  5. Nuclear Energy In Switzerland: It's going ahead. Challenges For The Swiss Nuclear Society Young Generation Group

    Energy Technology Data Exchange (ETDEWEB)

    Streit, Marco [Aare-Tessin Ltd for Electricity, Bahnhofquai 12, CH-4601 Olten (Switzerland); Bichsel, Thomas [BKW FMB Energie AG, NPP Muehleberg, CH-3203 Muehleberg (Switzerland); Fassbender, Andre [NPP Goesgen-Daeniken AG, CH-4658 Daeniken (Switzerland); Horvath, Matthias [National Emergency Operations Centre, CH-8044 Zurich (Switzerland)

    2008-07-01

    Swiss energy policy is focused on generating domestic electric power without combusting fossil fuels for already four decades. Roughly 60% of the electricity is generated in hydroelectric plants, which is possible due to the country's favourable topography; the remaining 40% are produced by the country's five nuclear power plants (NPPs). As in any other country nuclear power has its enemies in Switzerland. Due to the direct democracy system in Switzerland the nuclear opposition has a lot of possibilities to disturb the energy policy. Since 1969, when the first Swiss nuclear power plant went online, four plebiscites were held on the issue of civil use of nuclear energy. Four times Swiss citizens voted in favour of further operation of the existing plants also in the latest battle for nuclear energy, which was won in 2003. In 2005 and 2006 several Swiss studies about the future energy situation, especially the electricity situation, have been published. All off them show clearly that there will be a big gab around the year 2020 when the oldest three nuclear power plants will fade out. A public debate was started, how to solve the problem. Beside others, building new nuclear power plants was mentioned and discussed rationally. In 2007 the energy police of the Swiss government changed into a more nuclear friendly position and at the end of the same year some electricity companies lunched a new build program. Hosting the International Youth Nuclear Congress 2008 (IYNC 2008) in Switzerland seems to be just the right moment for the nuclear industry in our country. The slightly changed surroundings effected the organization of Swiss Nuclear Society (SNS) and SNS Young Generation Group (SNSYG) and enlarged the fields of activities for SNSYG. Those activities mentioned in the previous chapters will be developed in the future. The discussion about new builds in Switzerland has started and because of that more nuclear activities in Switzerland will occur. And surely

  6. Examining Quality Management Audits in Nuclear Medicine Practice as a lifelong learning process: opportunities and challenges to the nuclear medicine professional and beyond.

    Science.gov (United States)

    Pascual, Thomas N B

    2016-08-01

    This essay will explore the critical issues and challenges surrounding lifelong learning for professionals, initially exploring within the profession and organizational context of nuclear medicine practice. It will critically examine how the peer-review process called Quality Management Audits in Nuclear Medicine Practice (QUANUM) of the International Atomic Energy Agency (IAEA) can be considered a lifelong learning opportunity to instill a culture of quality to improve patient care and elevate the status of the nuclear medicine profession and practice within the demands of social changes, policy, and globalization. This will be explored initially by providing contextual background to the identity of the IAEA as an organization responsible for nuclear medicine professionals, followed by the benefits that QUANUM can offer. Further key debates surrounding lifelong learning, such as compulsification of lifelong learning and impact on professional change, will then be weaved through the discussion using theoretical grounding through a qualitative review of the literature. Keeping in mind that there is very limited literature focusing on the implications of QUANUM as a lifelong learning process for nuclear medicine professionals, this essay uses select narratives and observations of QUANUM as a lifelong learning process from an auditor's perspective and will further provide a comparative perspective of QUANUM on the basis of other lifelong learning opportunities such as continuing professional development activities and observe parallelisms on its benefits and challenges that it will offer to other professionals in other medical speciality fields and in the teaching profession.

  7. Structural Design Challenges in Design Certification Applications for New Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, M.; Braverman, J.; Wei, X.; Hofmayer, C.; Xu, J.

    2011-07-17

    The licensing framework established by the U.S. Nuclear Regulatory Commission under Title 10 of the Code of Federal Regulations (10 CFR) Part 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants,” provides requirements for standard design certifications (DCs) and combined license (COL) applications. The intent of this process is the early reso- lution of safety issues at the DC application stage. Subsequent COL applications may incorporate a DC by reference. Thus, the COL review will not reconsider safety issues resolved during the DC process. However, a COL application that incorporates a DC by reference must demonstrate that relevant site-specific de- sign parameters are confined within the bounds postulated by the DC, and any departures from the DC need to be justified. This paper provides an overview of structural design chal- lenges encountered in recent DC applications under the 10 CFR Part 52 process, in which the authors have participated as part of the safety review effort.

  8. Ran-dependent nuclear export mediators: a structural perspective.

    Science.gov (United States)

    Güttler, Thomas; Görlich, Dirk

    2011-08-31

    Nuclear export is an essential eukaryotic activity. It proceeds through nuclear pore complexes (NPCs) and is mediated by soluble receptors that shuttle between nucleus and cytoplasm. RanGTPase-dependent export mediators (exportins) constitute the largest class of these carriers and are functionally highly versatile. All of these exportins load their substrates in response to RanGTP binding in the nucleus and traverse NPCs as ternary RanGTP-exportin-cargo complexes to the cytoplasm, where GTP hydrolysis leads to export complex disassembly. The different exportins vary greatly in their substrate range. Recent structural studies of both protein- and RNA-specific exporters have illuminated how exportins bind their cargoes, how Ran triggers cargo loading and how export complexes are disassembled in the cytoplasm. Here, we review the current state of knowledge and highlight emerging principles as well as prevailing questions.

  9. Nuclear-structure studies of exotic nuclei with MINIBALL

    Science.gov (United States)

    Butler, P. A.; Cederkall, J.; Reiter, P.

    2017-04-01

    High-resolution γ-ray spectroscopy has been established at ISOLDE for nuclear-structure and nuclear-reaction studies with reaccelerated radioactive ion beams provided by the REX-ISOLDE facility. The MINIBALL spectrometer comprises 24 six-fold segmented, encapsulated high-purity germanium crystals. It was specially designed for highest γ-ray detection efficiency which is advantageous for low-intensity radioactive ion beams. The MINIBALL array has been used in numerous Coulomb-excitation and transfer-reaction experiments with exotic ion beams of energies up to 3 MeV A–1. The physics case covers a wide range of topics which are addressed with beams ranging from neutron-rich magnesium isotopes up to heavy radium isotopes. In the future the HIE-ISOLDE will allow the in-beam γ-ray spectroscopy program to proceed with higher secondary-beam intensity, higher beam energy and better beam quality.

  10. Actinide ion extraction using room temperature ionic liquids: opportunities and challenges for nuclear fuel cycle applications.

    Science.gov (United States)

    Mohapatra, Prasanta Kumar

    2017-02-14

    Studies on the extraction of actinide ions from radioactive feeds have great relevance in nuclear fuel cycle activities, mainly in the back end processes focused on reprocessing and waste management. Room temperature ionic liquid (RTIL) based diluents are becoming increasingly popular due to factors such as more efficient extraction vis-à-vis molecular diluents, higher metal loading, higher radiation resistance, etc. The fascinating chemistry of the actinide ions in RTIL based solvent systems due to complex extraction mechanisms makes it a challenging area of research. By the suitable tuning of the cationic and anionic parts of the ionic liquids, their physical properties such as density, dielectric constant and viscosity can be changed which are considered key parameters in metal ion extraction. Aqueous solubility of the RTILs, which can lead to significant loss in the solvent inventory, can be avoided by appending the extractant moieties onto the ionic liquid. While the low vapour pressure and non-flammability of the ionic liquids make them appear as 'green' diluents, their aqueous solubility raises concerns of environmental hazards. The present article gives a summary of studies carried out on actinide ion extraction and presents perspectives of its applications in the nuclear fuel cycle. The article discusses various extractants used for actinide ion extraction and at many places, comparison is made vis-à-vis molecular diluents which includes the nature of the extracted species and the mechanism of extraction. Results of studies on rare earth elements are also included in view of their similarities with the trivalent minor actinides.

  11. A challenging interpretation of a hexagonally layered protein structure

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Michael C.; Yeates, Todd O., E-mail: yeates@mbi.ucla.edu [UCLA, Los Angeles, CA 90095 (United States)

    2014-01-01

    The authors describe the structure determination of a hexagonally layered protein structure that suffered from a complicated combination of translational non-crystallographic symmetry and hemihedral twinning. This case serves as a reminder that broken crystallographic symmetry resulting from doubling of a unit-cell axis often requires a new choice of origin. The carboxysome is a giant protein complex that acts as a metabolic organelle in cyanobacteria and some chemoautotrophs. Its outer structure is formed by the assembly of thousands of copies of hexameric shell protein subunits into a molecular layer. The structure determination of a CcmK1 shell protein mutant (L11K) from the β-carboxysome of the cyanobacterium Synechocystis PCC6803 led to challenges in structure determination. Twinning, noncrystallographic symmetry and packing of hexameric units in a special arrangement led to initial difficulties in space-group assignment. The correct space group was clarified after initial model refinement revealed additional symmetry. This study provides an instructive example in which broken symmetry requires a new choice of unit-cell origin in order to identify the highest symmetry space group. An additional observation related to the packing arrangement of molecules in this crystal suggests that these hexameric shell proteins might have lower internal symmetry than previously believed.

  12. Computational challenges of structure-based approaches applied to HIV.

    Science.gov (United States)

    Forli, Stefano; Olson, Arthur J

    2015-01-01

    Here, we review some of the opportunities and challenges that we face in computational modeling of HIV therapeutic targets and structural biology, both in terms of methodology development and structure-based drug design (SBDD). Computational methods have provided fundamental support to HIV research since the initial structural studies, helping to unravel details of HIV biology. Computational models have proved to be a powerful tool to analyze and understand the impact of mutations and to overcome their structural and functional influence in drug resistance. With the availability of structural data, in silico experiments have been instrumental in exploiting and improving interactions between drugs and viral targets, such as HIV protease, reverse transcriptase, and integrase. Issues such as viral target dynamics and mutational variability, as well as the role of water and estimates of binding free energy in characterizing ligand interactions, are areas of active computational research. Ever-increasing computational resources and theoretical and algorithmic advances have played a significant role in progress to date, and we envision a continually expanding role for computational methods in our understanding of HIV biology and SBDD in the future.

  13. Adhesive bonding of composite aircraft structures: Challenges and recent developments

    Science.gov (United States)

    Pantelakis, Sp.; Tserpes, K. I.

    2014-01-01

    In this review paper, the challenges and some recent developments of adhesive bonding technology in composite aircraft structures are discussed. The durability of bonded joints is defined and presented for parameters that may influence bonding quality. Presented is also, a numerical design approach for composite joining profiles used to realize adhesive bonding. It is shown that environmental ageing and pre-bond contamination of bonding surfaces may degrade significantly fracture toughness of bonded joints. Moreover, it is obvious that additional research is needed in order to design joining profiles that will enable load transfer through shearing of the bondline. These findings, together with the limited capabilities of existing non-destructive testing techniques, can partially explain the confined use of adhesive bonding in primary composite aircraft structural parts.

  14. Challenges for Insertion of Structural Nanomaterials in Aerospace Applications

    Science.gov (United States)

    Sochi, Emilie J.

    2012-01-01

    In the two decades since Iijima's report on carbon nanotubes (CNT), there has been great interest in realizing the benefits of mechanical properties observed at the nanoscale in large-scale structures. The weight savings possible due to dramatic improvements in mechanical properties relative to state-of-the-art material systems can be game changing for applications like aerospace vehicles. While there has been significant progress in commercial production of CNTs, major aerospace applications that take advantage of properties offered by this material have yet to be realized. This paper provides a perspective on the technical challenges and barriers for insertion of CNTs as an emerging material technology in aerospace applications and proposes approaches that may reduce the typical timeframe for technology maturation and insertion into aerospace structures.

  15. Challenges in spent nuclear fuel final disposal:conceptual design models

    Institute of Scientific and Technical Information of China (English)

    Mukhtar Ahmed RANA

    2008-01-01

    The disposal of spent nuclear fuel is a long-standing issue in nuclear technology. Mainly, UO2 and metallic U are used as a fuel in nuclear reactors. Spent nuclear fuel contains fission products and transuranium elements, which would remain radioactive for 104 to 108 years. In this brief communication, essential concepts and engineering elements related to high-level nuclear waste disposal are described. Conceptual design models are described and discussed considering the long-time scale activity of spent nuclear fuel or high level waste. Notions of physical and chemical barriers to contain nuclear waste are highlightened. Concerns regarding integrity, self-irradiation induced decomposition and thermal effects of decay heat on the spent nuclear fuel are also discussed. The question of retrievability of spent nuclear fuel after disposal is considered.

  16. Structural control of the stability of nuclear waste glasses

    Science.gov (United States)

    Calas, G.; Galoisy, L.; Cormier, L.; Bergeron, B.; Jollivet, P.

    2009-05-01

    Vitrification of liquid high-level radioactive waste in borosilicate glasses has received a great attention in several countries. The fundamental properties of the waste forms are their chemical and mechanical durability. We present an overview of the local structure of inactive analogs of the French nuclear glass, using structural information obtained by a combination of X-ray absorption Fine Structure (XAFS) and Wide Angle X-ray Scattering (WAXS). We will first contrast several classes of elements, such as Zr, Mo or Zn, which give nuclear glasses peculiar positive or adverse properties for the industrial process: enhanced chemical stability, phase separation, crystal nucleation and separation. These properties may be rationalized using Pauling rules, familiar to Mineralogists, as other properties are correctly modelled in simplified glass compositions using molecular dynamics. We will also point out the importance of the melt-to-glass transition and the consequence of the glass structural properties on the resistance of glassy matrices to irradiation. Glass alteration affects the long-term stability of the glass. It is characterized by an amorphous (glass)-amorphous (gel) transformation. Depending on alteration conditions, alteration layers may have or not a protective character, which will influence radionuclide retention over time. We will present the structural modification of the surface chemistry of the glass monoliths during short-term experiments and the evolution towards a gel, which forms progressively at the expense of the glass. The protective character of the gel, observed during glass leaching under near-saturated conditions, will be rationalized by its structural properties.

  17. Seismic margin analysis technique for nuclear power plant structures

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jeong Moon; Choi, In Kil

    2001-04-01

    In general, the Seismic Probabilistic Risk Assessment (SPRA) and the Seismic Margin Assessment(SAM) are used for the evaluation of realistic seismic capacity of nuclear power plant structures. Seismic PRA is a systematic process to evaluate the seismic safety of nuclear power plant. In our country, SPRA has been used to perform the probabilistic safety assessment for the earthquake event. SMA is a simple and cost effective manner to quantify the seismic margin of individual structural elements. This study was performed to improve the reliability of SMA results and to confirm the assessment procedure. To achieve this goal, review for the current status of the techniques and procedures was performed. Two methodologies, CDFM (Conservative Deterministic Failure Margin) sponsored by NRC and FA (Fragility Analysis) sponsored by EPRI, were developed for the seismic margin review of NPP structures. FA method was originally developed for Seismic PRA. CDFM approach is more amenable to use by experienced design engineers including utility staff design engineers. In this study, detailed review on the procedures of CDFM and FA methodology was performed.

  18. Molecular structure and biological function of proliferating cell nuclear antigen

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Proliferating cell nuclear antigen (PCNA) is the core component of replication complex in eukaryote.As a processive factor of DNA polymerase delta, PCNA coordinates the replication process by interacting with various replication proteins. PCNA appears to play an essential role in many cell events, such as DNA damage repair, cell cycle regulation, and apoptosis, through the coordination or organization of different partners. PCNA is an essential factor in cell proliferation, and has clinical significance in tumor research. In this article we review the functional structure of PCNA, which acts as a function switch in different cell events.

  19. Nuclear effects in F_3 structure function of nucleon

    CERN Document Server

    Athar, M Sajjad; Vacas, M J Vicente

    2007-01-01

    We study nuclear effects in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio $R(x,Q^2)=\\frac{F^A_3(x,Q^2)}{AF^N_3(x, Q^2)}$ and the Gross-Llewellyn Smith(GLS) integral $G(x,Q^2)=\\int_x^1 dx F^A_3(x,Q^2)$ in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.

  20. Seismic design and analysis of nuclear power plant structures

    Institute of Scientific and Technical Information of China (English)

    Pentti Varpasuo

    2013-01-01

    The seismic design and analysis of nuclear power plant (NPP) begin with the seismic hazard assessment and design ground motion development for the site.The following steps are needed for the seismic hazard assessment and design ground motion development:a.the development of regional seismo-tectonic model with seismic source areas within 500 km radius centered to the site; b.the development of strong motion prediction equations;c.logic three development for taking into account uncertainties and seismic hazard quantification; d.the development of uniform hazard response spectra for ground motion at the site; e.simulation of acceleration time histories compatible with uniform hazard response spectra.The following phase two in seismic design of NPP structures is the analysis of structural response for the design ground motion.This second phase of the process consists of the following steps:a.development of structural models of the plant buildings; b.development of the soil model underneath the plant buildings for soil-structure interaction response analysis; c.determination of in-structure response spectra for the plant buildings for the equipment response analysis.In the third phase of the seismic design and analysis the equipment is analyzed on the basis of in-structure response spectra.For this purpose the structural models of the mechanical components and piping in the plant are set up.In large 3D-structural models used today the heaviest equipment of the primary coolant circuit is included in the structural model of the reactor building.In the fourth phase the electrical equipment and automation and control equipment are seismically qualified with the aid of the in-structure spectra developed in the phase two using large three-axial shaking tables.For this purpose the smoothed envelope spectra for calculated in-structure spectra are constructed and acceleration time is fitted to these smoothed envelope spectra.

  1. Structural technology challenges for evolutionary growth of Space Station Freedom

    Science.gov (United States)

    Doiron, Harold H.

    A proposed evolutionary growth scenario for Space Station Freedom was defined recently by a NASA task force created to study requirements for a Human Exploration Initiative. The study was an initial response to President Bush's July 20, 1989 proposal to begin a long range program of human exploration of space including a permanently manned lunar base and a manned mission to Mars. This growth scenario evolves Freedom into a critical transportation node to support lunar and Mars missions. The growth scenario begins with the Assembly Complete configuration and adds structure, power, and facilities to support a Lunar Transfer Vehicle (LTV) verification flight. Evolutionary growth continues to support expendable, then reusable LTV operations, and finally, LTV and Mars Transfer Vehicle (MTV) operations. The significant structural growth and additional operations creating new loading conditions will present new technological and structural design challenges in addition to the considerable technology requirements of the baseline Space Station Freedom program. Several structural design and technology issues of the baseline program are reviewed and related technology development required by the growth scenario is identified.

  2. Nuclear structure studies at Saha Institute of Nuclear Physics using gamma detector arrays

    Indian Academy of Sciences (India)

    P Banerjee

    2001-07-01

    In-beam gamma-ray spectroscopy, carried out at the Saha Institute of Nuclear Physics in the recent past, using heavy-ion projectiles from the pelletron accelerator centres in the country and multi-detector arrays have yielded significant data on the structure of a large number of nuclei spanning different mass regions. The experiments included the study of two-fold -coincidence events for establishing decay schemes, directional correlation of oriented nuclei (DCO) for help in spin assignments and Doppler shift attenuation for lifetime information. The studies have led to the observation of rotational sequences of states in nuclei near closed shell in the mass = 110 region, vibrational spectra in nuclei with ∼ 60, interplay between single-particle and collective modes of excitation in the doubly-odd bromine isotopes, decoupled bands with large quadrupole deformation in 77Br, shape transition with rotational frequency within a band in 138Pm and octupole collectivity in 153Eu. Particle-rotor-model and cranked-shell-model calculations have been carried out to provide an understanding of the underlying nuclear structure

  3. Reinforcement course 2013. Challenges at the operation end of nuclear power plants; Vertiefungskurs 2013. Herausforderungen am Betriebsende von Kernkraftwerken

    Energy Technology Data Exchange (ETDEWEB)

    Rey, Matthias [Nuklearforum Schweiz/Forum nucleaire suisse, Bern (Switzerland)

    2014-03-15

    The reinforcement course 2013 of the Nuclear Forum in Switzerland dedicated itself to the question, of which challenges are implicated by decommissioning and dismantling nuclear power plants. The course has been divided into 4 blocks, discussing concepts regarding decommissioning, special points such as organisational or psychological aspects as well as juridical and practical questions. Around 140 persons accepted the invitation of the committee for educational questions under the patronage of Urs Weidmann, head of the nuclear power plant Beznau. Altogether 17 presentations dealt with the following topics: 'Strategies and Steps of Decommissioning' by Roger Lundmark, 'Decommissioning from the Perspective of the Swiss Regulatory Authority' by Hannes Haenggi, 'Operating Period Management Using the Example of the Nuclear Power Plant Leibstadt' by Johannis Noeggerath, 'Questions and Concepts from the Perspective of a Nuclear Power Plant Operator' by Roland Schmidiger, 'Decommissioning of nuclear facilities in the UK' by Andrew Munro, 'Practical experiences of transferring nuclear power plants from operating to out of operation' by Gerd Reinstrom, 'Dismantling of Nuclear Facilities: From the Pilot Scheme to Industrialized Disassembling' by Anke Traichel and Thomas Seipolt, 'Organisational challenges: From Decommissioning Strategy to Decommissioning Targets' by Michael Kruse, Anton von Gunten, Julia Heizinger, Joerg Sokoll, 'Knowing That and Knowing How - Motivational Aspects of Safety-Related Knowledge Management for the Post-Operational phase and dismantling' by Frank Ritz, 'The Juridical Frame of Decommissioning' by Peter Koch, 'The Path to the Decommissioning Order and its Guidelines Ensi-G17' by Torsten Krietsch, 'Requirements for a Safe and Economical Decommissioning From the Perspective of the Operator' by Anton Von Gunten, Michael Kruse, Thomas

  4. Two citizen task forces and the challenge of the evolving nuclear waste siting process

    Energy Technology Data Exchange (ETDEWEB)

    Peelle, E.B.

    1990-01-01

    Siting any nuclear waste facility is problematic in today's climate of distrust toward nuclear agencies and fear of nuclear waste. This study compares and contrasts the siting and public participation processes as two citizen task forces dealt with their difficult responsibilities. 10 refs., 3 tabs.

  5. The Structure of Communication as a Challenge for Theology

    Directory of Open Access Journals (Sweden)

    Paul A Soukup

    2003-01-01

    Full Text Available ABSTRACT Even more than any content of communication, its structures influence theology by forming the framework for thinking about and sharing reflections on religious experience. This essay examines three characteristic, but often overlooked, communication structures: oral vs. written and printed communication and the contemporary move to "secondary oral" styles; communication technology's sense of place; and the uses of visual space as guides to the interpretation of experience. Since each of these structures shapes theology, a more conscious awareness of them challenges theology to take the role of communication more seriously.Aun más que cualquier contenido de la comunicación, sus estructuras influyen en la teología puesto que proporcionan el marco para el pensamiento y la reflexión de la experiencia religiosa. Este ensayo examina tres estructuras características de la comunicacion, que son a menudo pasadas por alto: la comunicación oral v/s la escrita e impresa y la tendencia contemporánea hacia los estilos "orales secundarios"; el sentido del lugar en la comunicación tecnológica; y los usos de espacio visual como guías de la interpretación de la experiencia. Puesto que cada una de estas estructuras moldean la teología, esta debiera asumir el desafío de tomar mayor conciencia de ellas y asumir el rol de la comunicación más seriamente.

  6. Structures and construction of nuclear power plants on lunar surface

    Science.gov (United States)

    Shimizu, Katsunori; Kobatake, Masuhiko; Ogawa, Sachio; Kanamori, Hiroshi; Okada, Yasuhiko; Mano, Hideyuki; Takagi, Kenji

    1991-07-01

    The best structure and construction techniques of nuclear power plants in the severe environments on the lunar surface are studied. Facility construction types (functional conditions such as stable structure, shield thickness, maintainability, safety distances, and service life), construction conditions (such as construction methods, construction equipment, number of personnel, time required for construction, external power supply, and required transportation) and construction feasibility (construction method, reactor transportation between the moon and the earth, ground excavation for installation, loading and unloading, transportation, and installation, filling up the ground, electric power supply of plant S (300 kW class) and plant L (3000 kW class)) are outlined. Items to pay attention to in construction are (1) automation and robotization of construction; (2) cost reduction by multi functional robots; and (3) methods of supplying power to robots. A precast concrete block manufacturing plant is also outlined.

  7. Chlorine Nuclear Quadrupole Hyperfine Structure in the Vinyl - Chloride Complex

    Science.gov (United States)

    Leung, Helen O.; Marshall, Mark D.; Messinger, Joseph P.

    2015-06-01

    The microwave spectrum of the vinyl chloride--hydrogen chloride complex, presented at last year's symposium, is greatly complicated by the presence of two chlorine nuclei as well as an observed, but not fully explained tunneling motion. Indeed, although it was possible at that time to demonstrate conclusively that the complex is nonplanar, the chlorine nuclear quadrupole hyperfine splitting in the rotational spectrum resisted analysis. With higher resolution, Balle-Flygare Fourier transform microwave spectra, the hyperfine structure has been more fully resolved, but appears to be perturbed for some rotational transitions. It appears that knowledge of the quadrupole coupling constants will provide essential information regarding the structure of the complex, specifically the location of the hydrogen atom in HCl. Our progress towards obtaining values for these constants will be presented.

  8. Potentially of using vertical and three dimensional isolation systems in nuclear structures

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Zhiuang [Research Institute of Structural Engineering and Disaster Reduction, Tongji University, Shanghai (China); Wong, Jenna [Lawrence Berkeley National Laboratories, Berkeley (United States); Mahin, Stephen [University of California, Berkeley (United States)

    2016-10-15

    Although the horizontal component of an earthquake response can be significantly reduced through the use of conventional seismic isolators, the vertical component of excitation is still transmitted directly into the structure. Records from instrumented structures, and some recent tests and analyses have actually seen increases in vertical responses in base isolated structures under the combined effects of horizontal and vertical ground motions. This issue becomes a great concern to facilities such as a Nuclear Power Plants (NPP), with specialized equipment and machinery that is not only expensive, but critical to safe operation. As such, there is considerable interest worldwide in vertical and three-dimensional (3D) isolation systems. This paper examines several vertical and 3D isolation systems that have been proposed and their potential application to modern nuclear facilities. In particular, a series of case study analyses of a modern NPP model are performed to examine the benefits and challenges associated with 3D isolation compared with horizontal isolation. It was found that compared with the general horizontal isolators, isolators that have vertical frequencies of no more than 3 Hz can effectively reduce the vertical in-structure responses for the studied NPP model. Among the studied cases, the case that has a vertical isolation frequency of 3 Hz is the one that can keep the horizontal period of the isolators as the first period while having the most flexible vertical isolator properties. When the vertical frequency of isolators reduces to 1 Hz, the rocking effect is obvious and rocking restraining devices are necessary.

  9. Geospatial Image Mining For Nuclear Proliferation Detection: Challenges and New Opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Vatsavai, Raju [ORNL; Bhaduri, Budhendra L [ORNL; Cheriyadat, Anil M [ORNL; Arrowood, Lloyd [Y-12 National Security Complex; Bright, Eddie A [ORNL; Gleason, Shaun Scott [ORNL; Diegert, Carl [Sandia National Laboratories (SNL); Katsaggelos, Aggelos K [ORNL; Pappas, Thrasos N [ORNL; Porter, Reid [Los Alamos National Laboratory (LANL); Bollinger, Jim [Savannah River National Laboratory (SRNL); Chen, Barry [Lawrence Livermore National Laboratory (LLNL); Hohimer, Ryan [Pacific Northwest National Laboratory (PNNL)

    2010-01-01

    With increasing understanding and availability of nuclear technologies, and increasing persuasion of nuclear technologies by several new countries, it is increasingly becoming important to monitor the nuclear proliferation activities. There is a great need for developing technologies to automatically or semi-automatically detect nuclear proliferation activities using remote sensing. Images acquired from earth observation satellites is an important source of information in detecting proliferation activities. High-resolution remote sensing images are highly useful in verifying the correctness, as well as completeness of any nuclear program. DOE national laboratories are interested in detecting nuclear proliferation by developing advanced geospatial image mining algorithms. In this paper we describe the current understanding of geospatial image mining techniques and enumerate key gaps and identify future research needs in the context of nuclear proliferation.

  10. NKS - The Nordic region's cooperative network for addressing challenges in nuclear safety and emergency preparedness

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, K.G. [NKS/Technical University of Denmark (Denmark); Andgren, K. [NKS/Vattenfall R and D (Sweden); Leino, K. [NKS/Fortum Power and Heat Oy (Finland); Magnusson, S. [NKS/Icelandic Radiation Safety Authority (Iceland); Physant, F. [NKS/FRIT, Roskilde (Denmark)

    2014-07-01

    Based on the foundation of a common cultural and historical heritage and a long tradition of collaboration, NKS aims to facilitate a common Nordic view on nuclear and radiation safety. A common understanding of rules, practice and measures, and national differences in this context, is here an essential requirement. Problems can generally be tackled quicker, more efficiently, more consistently and at a lower cost through collaboration, bearing in mind that key competencies are not equally distributed in the different Nordic countries. For instance common Nordic challenges emerge in relation to nuclear installations, where nuclear power plants are in operation in Finland and Sweden, and research reactors have been operated in Denmark, Finland, Norway and Sweden. There is an obvious benefit in exchanging ideas and technologies in relation to plant operation, and since a number of reactors in different Nordic countries are under decommissioning, a collaborative benefit can also be realised in that context. Sweden also has a nuclear fuel production plant, and its collaboration with other Nordic nuclear installations can also be beneficial. Further, a number of large radiological installations are projected in Nordic areas (e.g., the MAX-LAB/MAX IV synchrotron radiation source and the European spallation source ESS), where Nordic organisations are collaborating in addressing, e.g., potential environmental implications. On the emergency preparedness side, the Fukushima accident in March 2011 was a reminder that large accidents at nuclear installations can lead to widespread radioactive contamination in the environment. In order to respond to nuclear or radiological emergencies, should they affect Nordic populations, it is necessary to maintain an operational emergency preparedness. By continuously improving detection, response and decision aiding tools while maintaining an informal collaborative network between relevant stakeholders in the Nordic countries (including

  11. Physics with gamma-beams and charged particle detectors: I) Nuclear structure II) Nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Gai, Moshe [LNS at Avery Point, University of Connecticut, Groton, CT 06340-6097, USA and Wright Lab, Dept. of Physics, Yale University, New Haven, CT 06520-8124 and the Charged Particle Working Group (CPWG) of the Technical Design Report (TDR) (United States)

    2015-02-24

    The Charged Particle Working Group (CPWG) is proposing to construct large area Silicon Strip Detector (SSD), a gas Time Projection Chamber detector read by an electronic readout system (eTPC) and a Bubble Chamber (BC) containing superheated high purity water to be used in measurements utilizing intense gamma-ray beams from the newly constructed ELI-NP facility at Magurele, Bucharest in Romania. We intend to use the SSD and eTPC detectors to address essential problems in nuclear structure physics, such as clustering and the many alpha-decay of light nuclei such as {sup 12}C and {sup 16}O. All three detectors (SSD, eTPC and BC) will be used to address central problems in nuclear astrophysics such as the astrophysical cross section factor of the {sup 12}C(α,γ) reaction and other processes central to stellar evolution. The CPWG intends to submit to the ELI-NP facility a Technical Design Report (TDR) for the proposed detectors.

  12. Challenges predicting ligand-receptor interactions of promiscuous proteins: the nuclear receptor PXR.

    Directory of Open Access Journals (Sweden)

    Sean Ekins

    2009-12-01

    Full Text Available Transcriptional regulation of some genes involved in xenobiotic detoxification and apoptosis is performed via the human pregnane X receptor (PXR which in turn is activated by structurally diverse agonists including steroid hormones. Activation of PXR has the potential to initiate adverse effects, altering drug pharmacokinetics or perturbing physiological processes. Reliable computational prediction of PXR agonists would be valuable for pharmaceutical and toxicological research. There has been limited success with structure-based modeling approaches to predict human PXR activators. Slightly better success has been achieved with ligand-based modeling methods including quantitative structure-activity relationship (QSAR analysis, pharmacophore modeling and machine learning. In this study, we present a comprehensive analysis focused on prediction of 115 steroids for ligand binding activity towards human PXR. Six crystal structures were used as templates for docking and ligand-based modeling approaches (two-, three-, four- and five-dimensional analyses. The best success at external prediction was achieved with 5D-QSAR. Bayesian models with FCFP_6 descriptors were validated after leaving a large percentage of the dataset out and using an external test set. Docking of ligands to the PXR structure co-crystallized with hyperforin had the best statistics for this method. Sulfated steroids (which are activators were consistently predicted as non-activators while, poorly predicted steroids were docked in a reverse mode compared to 5alpha-androstan-3beta-ol. Modeling of human PXR represents a complex challenge by virtue of the large, flexible ligand-binding cavity. This study emphasizes this aspect, illustrating modest success using the largest quantitative data set to date and multiple modeling approaches.

  13. Metrology challenges for high-rate nanomanufacturing of polymer structures

    Science.gov (United States)

    Mead, Joey; Barry, Carol; Busnaina, Ahmed; Isaacs, Jacqueline

    2012-10-01

    The transfer of nanoscience accomplishments into commercial products is hindered by the lack of understanding of barriers to nanoscale manufacturing. We have developed a number of nanomanufacturing processes that leverage available high-rate plastics fabrication technologies. These processes include directed assembly of a variety of nanoelements, such as nanoparticles and nanotubes, which are then transferred onto a polymer substrate for the fabrication of conformal/flexible electronic materials, among other applications. These assembly processes utilize both electric fields and/or chemical functionalization. Conducting polymers and carbon nanotubes have been successfully transferred to a polymer substrate in times less than 5 minutes, which is commercially relevant and can be utilized in a continuous (reel to reel/roll to roll) process. Other processes include continuous high volume mixing of nanoelements (CNTs, etc) into polymers, multi-layer extrusion and 3D injection molding of polymer structures. These nanomanufacturing processes can be used for wide range of applications, including EMI shielding, flexible electronics, structural materials, and novel sensors (specifically for chem/bio detection). Current techniques to characterize the quality and efficacy of the processes are quite slow. Moreover, the instrumentation and metrology needs for these manufacturing processes are varied and challenging. Novel, rapid, in-line metrology to enable the commercialization of these processes is critically needed. This talk will explore the necessary measurement needs for polymer based nanomanufacturing processes for both step and continuous (reel to reel/roll to roll) processes.

  14. Pseudospin symmetry in nuclear structure and its supersymmetric representation

    CERN Document Server

    Liang, Haozhao

    2016-01-01

    The quasi-degeneracy between the single-particle states $(n,\\,l,\\,j=l+1/2)$ and $(n-1,\\,l+2,\\,j=l+3/2)$ indicates a special and hidden symmetry in atomic nuclei---the so-called pseudospin symmetry (PSS)---which is an important concept in both spherical and deformed nuclei. A number of phenomena in nuclear structure have been successfully interpreted directly or implicitly by this symmetry, including nuclear superdeformed configurations, identical bands, quantized alignment, pseudospin partner bands, and so on. Since the PSS was recognized as a relativistic symmetry in 1990s, there have been comprehensive efforts to understand its properties in various systems and potentials. In this Review, we mainly focus on the latest progress on the supersymmetric (SUSY) representation of PSS, and one of the key targets is to understand its symmetry-breaking mechanism in realistic nuclei in a quantitative and perturbative way. The SUSY quantum mechanics and its applications to the SU(2) and U(3) symmetries of the Dirac Ham...

  15. Ab Initio Nuclear Structure and Reaction Calculations for Rare Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Draayer, Jerry P. [Louisiana State Univ., Baton Rouge, LA (United States)

    2014-09-28

    We have developed a novel ab initio symmetry-adapted no-core shell model (SA-NCSM), which has opened the intermediate-mass region for ab initio investigations, thereby providing an opportunity for first-principle symmetry-guided applications to nuclear structure and reactions for nuclear isotopes from the lightest p-shell systems to intermediate-mass nuclei. This includes short-lived proton-rich nuclei on the path of X-ray burst nucleosynthesis and rare neutron-rich isotopes to be produced by the Facility for Rare Isotope Beams (FRIB). We have provided ab initio descriptions of high accuracy for low-lying (including collectivity-driven) states of isotopes of Li, He, Be, C, O, Ne, Mg, Al, and Si, and studied related strong- and weak-interaction driven reactions that are important, in astrophysics, for further understanding stellar evolution, X-ray bursts and triggering of s, p, and rp processes, and in applied physics, for electron and neutrino-nucleus scattering experiments as well as for fusion ignition at the National Ignition Facility (NIF).

  16. Pseudospin symmetry in nuclear structure and its supersymmetric representation

    Science.gov (United States)

    Liang, H. Z.

    2016-08-01

    The quasi-degeneracy between the single-particle states (n,l,j=l+1/2) and (n-1,l+2,j=l+3/2) indicates a special and hidden symmetry in atomic nuclei—the so-called pseudospin symmetry (PSS)—which is an important concept in both spherical and deformed nuclei. A number of phenomena in nuclear structure have been successfully interpreted directly or implicitly by this symmetry, including nuclear superdeformed configurations, identical bands, quantized alignment, pseudospin partner bands, and so on. Since the PSS was recognized as a relativistic symmetry in 1990s, there have been comprehensive efforts to understand its properties in various systems and potentials. In this review, we mainly focus on the latest progress on the supersymmetric (SUSY) representation of PSS, and one of the key targets is to understand its symmetry-breaking mechanism in realistic nuclei in a quantitative and perturbative way. The SUSY quantum mechanics and its applications to the SU(2) and U(3) symmetries of the Dirac Hamiltonian are discussed in detail. It is shown that the origin of PSS and its symmetry-breaking mechanism, which are deeply hidden in the origin Hamiltonian, can be traced by its SUSY partner Hamiltonian. Essential open questions, such as the SUSY representation of PSS in the deformed system, are pointed out.

  17. Nuclear structure of 216Ra at high spin

    Indian Academy of Sciences (India)

    S Muralithar; G Rodrigues; R P Singh; R K Bhowmik; P Mukherjee; B Sethi; I Mukherjee

    2012-09-01

    High-spin states of 216Ra ( = 88, = 128) have been investigated through 209Bi(10B, 3n) reaction at an incident beam energy of 55 MeV and 209Bi(11B, 4n) reaction at incident beam energies ranging from 65 to 78 MeV. Based on coincidence data, the level scheme for 216Ra has been considerably extended up to $∼ 33\\hbar$ spin and 7.2 MeV excitation energy in the present experiment with placement of 28 new -transitions over what has been reported earlier. Tentative spin-parity assignments are done for the newly proposed levels on the basis of the DCO ratios corresponding to strong gates. Empirical shell model calculations were carried out to provide an understanding of the underlying nuclear structure.

  18. Nuclear Structure of N $\\simeq$ 56 Krypton Isotopes

    CERN Multimedia

    2002-01-01

    In view of the strong overlap in subject matter, the proposals IP-39 and 40 were considered together by the ISOLDE-Committee, and a combined investigation was suggested to be presented to the PSCC.\\\\ \\\\ First results on $\\beta$-decay properties of very neutron-rich Br isotopes (Z=35) indicate a rather smooth onset of deformation already below N=60 and the existence of a deformed N=56 subshell gap. This behaviour is in contrast to earlier observations of a sudden onset of strong deformations at N=60 for $ \\% Z ge $ 37 nuclei. \\\\ \\\\ We propose to study at CERN-ISOLDE nuclear structure properties of N=55 - 57 Kr isotopes from $\\beta$-decay of $^9

  19. Structure of nuclear transition matrix elements for neutrinoless double- decay

    Indian Academy of Sciences (India)

    P K Rath

    2010-08-01

    The structure of nuclear transition matrix elements (NTMEs) required for the study of neutrinoless double- decay within light Majorana neutrino mass mechanism is disassembled in the PHFB model. The NTMEs are calculated using a set of HFB intrinsic wave functions, the reliability of which has been previously established by obtaining an overall agreement between the theoretically calculated spectroscopic properties and the available experimental data. Presently, we study the role of short-range correlations, radial evolution of NTMEs and deformation effects due to quadrupolar correlations. In addition, limits on effective light neutrino mass $\\langle m_{} \\rangle$ are extracted from the observed limits on half-lives $T_{1/2}^{0}$ of neutrinoless double- decay.

  20. Nuclear structure studies. Progress report, [1988--1994

    Energy Technology Data Exchange (ETDEWEB)

    Walters, W.B.

    1993-07-31

    In this report, newly initiated work at the FMA is described where the use of double-sided strip detectors for charged particle spectroscopy on nuclides near the proton drip line has been investigated. Half lives for proton emitting nuclides have been determined with improved uncertainties. Several sections report on the results of studies of model parameters in the Z = 50 region for even-even nuclides, for odd-mass nuclides and for odd-odd nuclides. Other studies are reported for nuclear orientation in Br and for structure of Pr-147 which lies in a transition zone between reflection-asymmetric, spherical, and prolate nuclides. And there is a section in which the positions of the single Particle levels in the A = 100 region are discussed.

  1. Considerations for a US Nuclear Force Structure below a 1,000-Warhead Limit

    Science.gov (United States)

    2011-01-01

    discussion between the two counties on tactical nuclear weapons.13 By 26 January 2011 both the Russian State Duma and Federation Council ratified the...country brings to the table. The challenge is to coordinate the step-by-step disarmament of the nine current members of the nuclear weapons club while

  2. Particle accelerators and nuclear energy: the challenge of reliability; Acceleradores de particulas y energia nuclear: el desafio de la fiabilidad

    Energy Technology Data Exchange (ETDEWEB)

    Brucker, R.; Fernandez Ramos, P.

    2011-07-01

    High energy particle accelerators, that used to serve a purpose only in fundamental research, will soon be used in industrial applications of nuclear energy. In this context, they will be submitted to unprecedented (as far as such machines are concerned) reliability requirements. In order to meet them, reliability studies need to be carried out. This article describes the experience gained by Empresarios Agrupados in that field (with the Eurotrans and Ifmif projects) and presents their future activities in the framework of the Myrrha project, that is aimed at building the first ADS reactor in the world. (Author)

  3. Challenges in Cost Estimation under Uncertainty—A Case Study of the Decommissioning of Barsebäck Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Olav Torp

    2016-10-01

    Full Text Available Cost estimation is an important part of project planning. Over the years different approaches have developed, taking uncertainty into account in the cost estimation processes in order to tackle the dynamic nature of projects. However, when implementing these approaches, some challenges have been revealed. The aim in a cost estimation process is to establish a realistic overview of the total project costs and its uncertainties. Even though tools and methods for taking uncertainty into account are implemented, projects with cost overruns are often seen. In this paper we look into some challenges with the practice in cost estimation processes and identify possible improvements to overcome them. The purpose of this paper is to illustrate better solutions to some of the major weaknesses identified in current cost estimation practice. We use a case study of decommissioning of Barsebäck Nuclear Power Plant to illustrate how to overcome these challenges. First of all, this is an interesting case with challenges related to the project and the cost estimation process, given the complexity in the situation and that very few have experiences related to decommission of nuclear power plants. Second, we applied an approach that is not yet commonly used to develop cost estimates for this kind of projects. The paper concludes that it is possible to improve the results of uncertainty analysis of cost estimates. A well prepared process, with a suitable group of experts that go through a well-structured process, focusing both on risks and opportunities and using a top-down approach can compensate for some of the challenges related to cost estimation under uncertainty.

  4. Nuclear Physics

    CERN Document Server

    Savage, Martin J

    2016-01-01

    Lattice QCD is making good progress toward calculating the structure and properties of light nuclei and the forces between nucleons. These calculations will ultimately refine the nuclear forces, particularly in the three- and four-nucleon sector and the short-distance interactions of nucleons with electroweak currents, and allow for a reduction of uncertainties in nuclear many-body calculations of nuclei and their reactions. After highlighting their importance, particularly to the Nuclear Physics and High-Energy Physics experimental programs, I discuss the progress that has been made toward achieving these goals and the challenges that remain.

  5. Understanding the proton radius puzzle: Nuclear structure effects in light muonic atoms

    CERN Document Server

    Ji, Chen; Dinur, Nir Nevo; Bacca, Sonia; Barnea, Nir

    2015-01-01

    We present calculations of nuclear structure effects to the Lamb shift in light muonic atoms. We adopt a modern ab-initio approach by combining state-of-the-art nuclear potentials with the hyperspherical harmonics method. Our calculations are instrumental to the determination of nuclear charge radii in the Lamb shift measurements, which will shed light on the proton radius puzzle.

  6. Nuclear Structure at the Legnaro National Laboratories:. from High Intensity Stable to Radioactive Nuclear Beams

    Science.gov (United States)

    de Angelis, G.

    2007-04-01

    To understand the properties of a nucleus, apart from establishing the interaction between its components, it is necessary to determine the arrangement of the nucleons, i.e. the structure of a nucleus. So far our knowledge about the structure of nuclei is mostly limited to nuclei close to the valley of stability, or nuclei with a deficiency of neutrons, which can be produced in fusion-evaporation reactions with stable beams and stable targets. Future perspectives in nuclear structure rely on radioactive ion beams (RIB) as well as on high intensity beams of stable ions (HISB). A world wide effort is presently going on in order to built the next generation radioactive ion beam facilities like the FAIR and the EURISOL projects. The LNL are contributing to such development through the design study of the EURISOL project as well as through the design and construction of the intermediate facility SPES. Concerning the instrumentation, particularly powerful is the combination of large acceptance spectrometers with highly segmented γ-detector arrays. An example is the CLARA γ-ray detector array coupled with the PRISMA spectrometer at the Legnaro National Laboratories (LNL). The physics aims achievable with such device complement studies performed with current radioactive beam (RIB) facilities. With this set-up we have recently investigated the stability of the N=50 shell closure. Here the comparison of the experimental data with shell model calculations seems to indicate a persistence of the N=50 shell gap down to Z=31. Also the study of proton rich nuclei can strongly benefit from the use of high intensity stable beams using fusion evaporation reactions at energies close to the Coulomb barrier. Future perspectives at LNL are based on an increase in intensity as well as on the availability of heavy ion species. Moreover a new ISOL facility (SPES) dedicated to the production and acceleration of radioactive neutron rich species is now under development at LNL. Among the new

  7. The challenges and importance of structural variation detection in livestock

    Directory of Open Access Journals (Sweden)

    Derek M Bickhart

    2014-02-01

    Full Text Available Recent studies in humans and other model organisms have demonstrated that structural variants (SVs comprise a substantial proportion of variation among individuals of each species. Many of these variants have been linked to debilitating diseases in humans, thereby cementing the importance of refining methods for their detection. Despite progress in the field, reliable detection of SVs still remains a problem even for human subjects. Many of the underlying problems that make SVs difficult to detect in humans are amplified in livestock species, whose lower quality genome assemblies and incomplete gene annotation can often give rise to false positive SV discoveries. Regardless of the challenges, SV detection is just as important for livestock researchers as it is for human researchers, given that several productive traits and diseases have been linked to Copy Number Variations (CNVs in cattle, sheep and pig. Already, there is evidence that many beneficial SVs have been artificially selected in livestock such as a duplication of the ASIP gene that causes white coat color in sheep. In this review, we will list current SV and CNV discoveries in livestock and discuss the problems that hinder routine discovery and tracking of these polymorphisms. We will also discuss the impacts of selective breeding on CNV and SV frequencies and mention how SV genotyping could be used in the future to improve genetic selection.

  8. Correlating structure and function of drug-metabolizing enzymes: progress and ongoing challenges.

    Science.gov (United States)

    Johnson, Eric F; Connick, J Patrick; Reed, James R; Backes, Wayne L; Desai, Manoj C; Xu, Lianhong; Estrada, D Fernando; Laurence, Jennifer S; Scott, Emily E

    2014-01-01

    This report summarizes a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics at Experimental Biology held April 20-24 in Boston, MA. Presentations discussed the status of cytochrome P450 (P450) knowledge, emphasizing advances and challenges in relating structure with function and in applying this information to drug design. First, at least one structure of most major human drug-metabolizing P450 enzymes is known. However, the flexibility of these active sites can limit the predictive value of one structure for other ligands. A second limitation is our coarse-grain understanding of P450 interactions with membranes, other P450 enzymes, NADPH-cytochrome P450 reductase, and cytochrome b5. Recent work has examined differential P450 interactions with reductase in mixed P450 systems and P450:P450 complexes in reconstituted systems and cells, suggesting another level of functional control. In addition, protein nuclear magnetic resonance is a new approach to probe these protein/protein interactions, identifying interacting b5 and P450 surfaces, showing that b5 and reductase binding are mutually exclusive, and demonstrating ligand modulation of CYP17A1/b5 interactions. One desired outcome is the application of such information to control drug metabolism and/or design selective P450 inhibitors. A final presentation highlighted development of a CYP3A4 inhibitor that slows clearance of human immunodeficiency virus drugs otherwise rapidly metabolized by CYP3A4. Although understanding P450 structure/function relationships is an ongoing challenge, translational advances will benefit from continued integration of existing and new biophysical approaches.

  9. Are There Nuclear Structure Effects on the Isoscalar Giant Monopole Resonance and Nuclear Incompressibility near A~90?

    CERN Document Server

    Gupta, Y K; Howard, K B; Matta, J T; Senyigit, M; Itoh, M; Ando, S; Aoki, T; Uchiyama, A; Adachi, S; Fujiwara, M; Iwamoto, C; Tamii, A; Akimune, H; Kadono, C; Matsuda, Y; Nakahara, T; Furuno, T; Kawabata, T; Tsumura, M; Harakeh, M N; Kalantar-Nayestanaki, N

    2016-01-01

    "Background-free" spectra of inelastic $\\alpha$-particle scattering have been measured at a beam energy of 385 MeV in $^{90, 92}$Zr and $^{92}$Mo at extremely forward angles, including 0$^{\\circ}$. The ISGMR strength distributions for the three nuclei coincide with each other, establishing clearly that nuclear incompressibility is not influenced by nuclear shell structure near $A\\sim$90 as was claimed in recent measurements.

  10. Probing nuclear structure with nucleons; Sonder la structure nucleaire avec des nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Bauge, E. [CEA Bruyeres-le-Chatel, Service de Physique Nucl aire, 91 (France)

    2007-07-01

    The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)

  11. Nuclear nonproliferation and safety: Challenges facing the International Atomic Energy Agency

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    The Chairman of the Senate Committee on Govermental Affairs asked the United States General Accounting Office (GAO) to review the safeguards and nuclear power plant safety programs of the International Atomic Energy Agency (IAEA). This report examines (1) the effectiveness of IAEA`s safeguards program and the adequacy of program funding, (2) the management of U.S. technical assistance to the IAEA`s safeguards program, and (3) the effectiveness of IAEA`s program for advising United Nations (UN) member states about nuclear power plant safety and the adequacy of program funding. Under its statute and the Treaty on the Non-Proliferation of Nuclear Weapons, IAEA is mandated to administer safeguards to detect diversions of significant quantities of nuclear material from peaceful uses. Because of limits on budget growth and unpaid contributions, IAEA has had difficulty funding the safeguards program. IAEA also conducts inspections of facilities or locations containing declared nuclear material, and manages a program for reviewing the operational safety of designated nuclear power plants. The U.S. technical assistance program for IAEA safeguards, overseen by an interagency coordinating committee, has enhanced the agency`s inspection capabilities, however, some weaknesses still exist. Despite financial limitations, IAEA is meeting its basic safety advisory responsibilities for advising UN member states on nuclear safety and providing requested safety services. However, IAEA`s program for reviewing the operational safety of nuclear power plants has not been fully effective because the program is voluntary and UN member states have not requested IAEA`s review of all nuclear reactors with serious problems. GAO believes that IAEA should have more discretion in selecting reactors for review.

  12. Nuclear containment structure subjected to commercial and fighter aircraft crash

    Energy Technology Data Exchange (ETDEWEB)

    Sadique, M.R., E-mail: rehan.sadique@gmail.com; Iqbal, M.A., E-mail: iqbalfce@iitr.ernet.in; Bhargava, P., E-mail: bhpdpfce@iitr.ernet.in

    2013-07-15

    Highlights: • Nuclear containment response has been studied against aircraft crash. • Concrete damaged plasticity and Johnson–Cook elasto-viscoplastic models were employed. • Boeing 747-400 and Boeing 767-400 aircrafts caused global failure of containment. • Airbus A320 and Boeing 707-320 aircrafts caused local damage. • Tension damage of concrete was found more prominent compared to compression damage. -- Abstract: The response of a boiling water reactor (BWR) nuclear containment vessel has been studied against commercial and fighter aircraft crash using a nonlinear finite element code ABAQUS. The aircrafts employed were Boeing 747-400, Boeing 767-400, Airbus A-320, Boeing 707-320 and Phantom F4. The containment was modeled as a three-dimensional deformable reinforced concrete structure while the loading of aircraft was assigned using the respective reaction–time curve. The location of strike was considered near the junction of dome and cylinder, and the angle of incidence, normal to the containment surface. The material behavior of the concrete was incorporated using the damaged plasticity model while that of the reinforcement, the Johnson–Cook elasto-viscoplastic model. The containment could not sustain the impact of Boeing 747-400 and Boeing 767-400 aircrafts and suffered rupture of concrete around the impact region leading to global failure. On the other hand, the maximum local deformation at the point of impact was found to be 0.998 m, 0.099 m, 0.092 m, 0.089 m, and 0.074 m against Boeing 747-400, Phantom F4, Boeing 767, Boeing 707-320 and Airbus A-320 aircrafts respectively. The results of the present study were compared with those of the previous analytical and numerical investigations with respect to the maximum deformation and overall behavior of the containment.

  13. Summary. “Materials Challenges in Nuclear Energy,” S.J. Zinkle, 2013

    Energy Technology Data Exchange (ETDEWEB)

    Pestovich, Kimberly Shay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-05

    Nuclear energy continues to grow in abundance and importance. It offers a future electric grid based entirely off of green energy, and it has numerous applications. Nuclear power has capabilities to desalinate water, deliver process heat or steam, affordably crack hydrogen from water, and extract unconventional fossil fuel sources. Current light water reactors demonstrate high reliability under normal operating conditions. Researchers have shown significant interest and investigating how to extend reactor lifespans and into other possible reactor designs. Further understanding of mechanisms responsible for corrosion and stress corrosion cracking, radiation hardening and degradation, and nuclear fuels innovations can lead to safer, more reliable, and cost-effective water-cooled nuclear reactors for electricity production.

  14. Supporting Teachers in Structuring Mathematics Lessons Involving Challenging Tasks

    Science.gov (United States)

    Sullivan, Peter; Askew, Mike; Cheeseman, Jill; Clarke, Doug; Mornane, Angela; Roche, Anne; Walker, Nadia

    2015-01-01

    The following is a report on an investigation into ways of supporting teachers in converting challenging mathematics tasks into classroom lessons and supporting students in engaging with those tasks. Groups of primary and secondary teachers, respectively, were provided with documentation of ten lessons built around challenging tasks. Teachers…

  15. Asia’s Major Powers and the Emerging Challenges to Nuclear Stability Among Them

    Science.gov (United States)

    2009-02-01

    political and economic factors to consider. In Russia, policies will debated in the Duma , where many competing economic, political, and military...welcome a reunified Korea to the club of nuclear-armed democracies, mismanage its strategic competition with China in a way that magnifies Chinese...expanding the pool of allies, extending additional forms of deterrence, and possibly also growing the club of nuclear-armed democracies. In the

  16. {\\it Ab initio} nuclear structure - the large sparse matrix eigenvalue problem

    CERN Document Server

    Vary, James P; Ng, Esmond; Yang, Chao; Sosonkina, Masha

    2009-01-01

    The structure and reactions of light nuclei represent fundamental and formidable challenges for microscopic theory based on realistic strong interaction potentials. Several {\\it ab initio} methods have now emerged that provide nearly exact solutions for some nuclear properties. The {\\it ab initio} no core shell model (NCSM) and the no core full configuration (NCFC) method, frame this quantum many-particle problem as a large sparse matrix eigenvalue problem where one evaluates the Hamiltonian matrix in a basis space consisting of many-fermion Slater determinants and then solves for a set of the lowest eigenvalues and their associated eigenvectors. The resulting eigenvectors are employed to evaluate a set of experimental quantities to test the underlying potential. For fundamental problems of interest, the matrix dimension often exceeds $10^{10}$ and the number of nonzero matrix elements may saturate available storage on present-day leadership class facilities. We survey recent results and advances in solving t...

  17. Nuclear Structure and Nuclear Astrophysics Studies with Fast Heavy-Ion Beams

    Science.gov (United States)

    Motobayashi, Tohru

    Collaboration between France and Japan on studies with fast RI (radioactive isotope) beams and related technical developments started in 1980s, when the GANIL accelerators and RIKEN cyclotron complex started operation and RI beam production technique was developed. Several examples of collaboration on nuclear physics and nuclear astrophysics experiments including related technical development are discussed.

  18. Nuclear structure and reaction studies at medium energies

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, G.W.; Ray, R.L.

    1990-10-01

    This document constitutes the (1988--1991) technical progress report for the ongoing medium energy physics research program supported by the US Department of Energy through special Research Grant FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF), the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL), and at the Fermi National Accelerator Laboratory (FNAL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics;(2) provide unique, first-of-a-kind exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics.

  19. The shell model. Towards a unified description of nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Poves, Alfredo [Departamento de Fisica Teorica, Universidad Autonoma Cantoblanco, 28049 - Madrid (Spain); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    In this series of lectures we present the foundations of the spherical shell model that we treat as an approximation to the exact solution of the full secular problem. We introduce the notions of valence space, effective interaction and effective operator. We analyse the structure of the realistic effective interactions, identifying their monopole part with the spherical mean field. The multipole Hamiltonian is shown to have a universal (simple) form that includes pairing (isovector and isoscalar), quadrupole, octupole, deca-pole, and ({sigma}{center_dot}{tau})({sigma}{center_dot}{tau}). We describe the methods of resolution of the secular problem, in particular the Lanczos method. The model is applied to the description of nuclear deformation and its relationship with the deformed mean field theories is studied. We propose a new symmetry, `quasi`-SU3, to understand deformation in the spherical basis. Finally, we discuss the domain of nuclei very far from the valley of {beta} stability, addressing the vanishing of some magic closures that can be explained in terms of intruder states. (author) 53 refs., 20 figs., 3 tabs.

  20. Nucleus-Dependent Valence-Space Approach to Nuclear Structure

    Science.gov (United States)

    Stroberg, S. R.; Calci, A.; Hergert, H.; Holt, J. D.; Bogner, S. K.; Roth, R.; Schwenk, A.

    2017-01-01

    We present a nucleus-dependent valence-space approach for calculating ground and excited states of nuclei, which generalizes the shell-model in-medium similarity renormalization group to an ensemble reference with fractionally filled orbitals. Because the ensemble is used only as a reference, and not to represent physical states, no symmetry restoration is required. This allows us to capture three-nucleon (3 N ) forces among valence nucleons with a valence-space Hamiltonian specifically targeted to each nucleus of interest. Predicted ground-state energies from carbon through nickel agree with results of other large-space ab initio methods, generally to the 1% level. In addition, we show that this new approach is required in order to obtain convergence for nuclei in the upper p and s d shells. Finally, we address the 1+/3+ inversion problem in 22Na and 46V. This approach extends the reach of ab initio nuclear structure calculations to essentially all light- and medium-mass nuclei.

  1. Monitoring the Geneseo Nuclear Structure Lab with VISION

    Science.gov (United States)

    Nicklaw, R.; Padalino, S.; McLean, J.

    2002-10-01

    VISION (Virtual Instrument System Information) is a LabVIEW based program designed to monitor a 2 MV Van de Graaff accelerator in the Geneseo Nuclear Structure Laboratory (GNSL). The purpose of the system is to monitor and notify the user of potentially critical situations in the lab. Main parameters of interest are the water coolant temperatures in the diffusion pumps, pressures within the vacuum chambers, and Van de Graaff operational parameters. LabVIEW reads these values and then displays them on monitors located throughout the laboratory. The user can set alarm limits on the relevant parameters, and when exceeded notifies the user verbally and visually. Recent additions to the VISION program include the water level sensor, calibration of the pressure readings, a web server application, and data logging. The VISION system is Internet accessible ^1, data from the main screen is displayed over the web for remote monitoring of the accelerator. Another useful monitoring tool is the data logger, which writes acquired data to a formatted text document at specified intervals. A future goal for VISION is to not only monitor, but to control aspects of the GNSL with LabVIEW. ^1 Webpage accessible at: http://s69n144.sci.geneseo.edu/vision.htm * Research funded in part by the United States Department of Energy

  2. Potentiality of Using Vertical and Three-Dimensional Isolation Systems in Nuclear Structures

    Directory of Open Access Journals (Sweden)

    Zhiguang Zhou

    2016-10-01

    Full Text Available Although the horizontal component of an earthquake response can be significantly reduced through the use of conventional seismic isolators, the vertical component of excitation is still transmitted directly into the structure. Records from instrumented structures, and some recent tests and analyses have actually seen increases in vertical responses in base isolated structures under the combined effects of horizontal and vertical ground motions. This issue becomes a great concern to facilities such as a Nuclear Power Plants (NPP, with specialized equipment and machinery that is not only expensive, but critical to safe operation. As such, there is considerable interest worldwide in vertical and three-dimensional (3D isolation systems. This paper examines several vertical and 3D isolation systems that have been proposed and their potential application to modern nuclear facilities. In particular, a series of case study analyses of a modern NPP model are performed to examine the benefits and challenges associated with 3D isolation compared with horizontal isolation. It was found that compared with the general horizontal isolators, isolators that have vertical frequencies of no more than 3 Hz can effectively reduce the vertical in-structure responses for the studied NPP model. Among the studied cases, the case that has a vertical isolation frequency of 3 Hz is the one that can keep the horizontal period of the isolators as the first period while having the most flexible vertical isolator properties. When the vertical frequency of isolators reduces to 1 Hz, the rocking effect is obvious and rocking restraining devices are necessary.

  3. Nuclear and plastid genetic engineering of plants: comparison of opportunities and challenges.

    Science.gov (United States)

    Meyers, Benjamin; Zaltsman, Adi; Lacroix, Benoît; Kozlovsky, Stanislav V; Krichevsky, Alexander

    2010-01-01

    Plant genetic engineering is one of the key technologies for crop improvement as well as an emerging approach for producing recombinant proteins in plants. Both plant nuclear and plastid genomes can be genetically modified, yet fundamental functional differences between the eukaryotic genome of the plant cell nucleus and the prokaryotic-like genome of the plastid will have an impact on key characteristics of the resulting transgenic organism. So, which genome, nuclear or plastid, to transform for the desired transgenic phenotype? In this review we compare the advantages and drawbacks of engineering plant nuclear and plastid genomes to generate transgenic plants with the traits of interest, and evaluate the pros and cons of their use for different biotechnology and basic research applications, ranging from generation of commercial crops with valuable new phenotypes to 'bioreactor' plants for large-scale production of recombinant proteins to research model plants expressing various reporter proteins.

  4. Investigations of nuclear structure and nuclear reactions induced by complex projectiles. Progress report, September 1, 1991--August 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Sarantites, D.G.

    1992-12-01

    The research program described touches five areas of nuclear physics: nuclear structure studies at high spin (hyperdeformation in the mass A {approx_equal} 182 region, structure of {sup 182}Hg and {sup 182}Au at high spin, a highly deformed band in {sup 136}Pm and the anomalous h{sub 11/2} proton crossing in the A{approximately}135 superdeformed region), studies at the interface between structure and reactions (population of entry states in heavy-ion fusion reactions, nuclear structure effects in proton evaporation spectra, nuclear structure- dependent entry state population by total spectroscopy, entrance channel effects in fusion near the barrier, lifetimes of subbarrier {alpha} particles by the atomic clock method), production and study of hot nuclei (the statistical model evaporation code EVAP, statistical emission of deuterons and tritons from highly excited compound nuclei, heavy-fragment emission as a probe of the thermal properties of highly excited compound nuclei, use of incoming-wave boundary condition transmission coefficients in the statistical model: implications in the particle evaporation spectra, study of transparency in the optical model), reaction mechanism studies (binary character of highly dissipative {sup 209}Bi + {sup 136}Xe collisions at E/A=28.2 MeV), and development and use of novel techniques and instrumentation in these areas of research (including a 4{pi} channel selection device, a novel x-ray detector, and a simple channel-selecting detector).

  5. Investigations of nuclear structure and nuclear reactions induced by complex projectiles. [Dept. of Chemistry, Washington Univ. , St. Louis, Mo

    Energy Technology Data Exchange (ETDEWEB)

    Sarantites, D.G.

    1992-01-01

    The research program described touches five areas of nuclear physics: nuclear structure studies at high spin (hyperdeformation in the mass A [approx equal] 182 region, structure of [sup 182]Hg and [sup 182]Au at high spin, a highly deformed band in [sup 136]Pm and the anomalous h[sub 11/2] proton crossing in the A[approximately]135 superdeformed region), studies at the interface between structure and reactions (population of entry states in heavy-ion fusion reactions, nuclear structure effects in proton evaporation spectra, nuclear structure- dependent entry state population by total spectroscopy, entrance channel effects in fusion near the barrier, lifetimes of subbarrier [alpha] particles by the atomic clock method), production and study of hot nuclei (the statistical model evaporation code EVAP, statistical emission of deuterons and tritons from highly excited compound nuclei, heavy-fragment emission as a probe of the thermal properties of highly excited compound nuclei, use of incoming-wave boundary condition transmission coefficients in the statistical model: implications in the particle evaporation spectra, study of transparency in the optical model), reaction mechanism studies (binary character of highly dissipative [sup 209]Bi + [sup 136]Xe collisions at E/A=28.2 MeV), and development and use of novel techniques and instrumentation in these areas of research (including a 4[pi] channel selection device, a novel x-ray detector, and a simple channel-selecting detector).

  6. Nucleoporins as components of the nuclear pore complex core structure and Tpr as the architectural element of the nuclear basket.

    Science.gov (United States)

    Krull, Sandra; Thyberg, Johan; Björkroth, Birgitta; Rackwitz, Hans-Richard; Cordes, Volker C

    2004-09-01

    The vertebrate nuclear pore complex (NPC) is a macromolecular assembly of protein subcomplexes forming a structure of eightfold radial symmetry. The NPC core consists of globular subunits sandwiched between two coaxial ring-like structures of which the ring facing the nuclear interior is capped by a fibrous structure called the nuclear basket. By postembedding immunoelectron microscopy, we have mapped the positions of several human NPC proteins relative to the NPC core and its associated basket, including Nup93, Nup96, Nup98, Nup107, Nup153, Nup205, and the coiled coil-dominated 267-kDa protein Tpr. To further assess their contributions to NPC and basket architecture, the genes encoding Nup93, Nup96, Nup107, and Nup205 were posttranscriptionally silenced by RNA interference (RNAi) in HeLa cells, complementing recent RNAi experiments on Nup153 and Tpr. We show that Nup96 and Nup107 are core elements of the NPC proper that are essential for NPC assembly and docking of Nup153 and Tpr to the NPC. Nup93 and Nup205 are other NPC core elements that are important for long-term maintenance of NPCs but initially dispensable for the anchoring of Nup153 and Tpr. Immunogold-labeling for Nup98 also results in preferential labeling of NPC core regions, whereas Nup153 is shown to bind via its amino-terminal domain to the nuclear coaxial ring linking the NPC core structures and Tpr. The position of Tpr in turn is shown to coincide with that of the nuclear basket, with different Tpr protein domains corresponding to distinct basket segments. We propose a model in which Tpr constitutes the central architectural element that forms the scaffold of the nuclear basket.

  7. Automatic classification of hepatocellular carcinoma images based on nuclear and structural features

    Science.gov (United States)

    Kiyuna, Tomoharu; Saito, Akira; Marugame, Atsushi; Yamashita, Yoshiko; Ogura, Maki; Cosatto, Eric; Abe, Tokiya; Hashiguchi, Akinori; Sakamoto, Michiie

    2013-03-01

    Diagnosis of hepatocellular carcinoma (HCC) on the basis of digital images is a challenging problem because, unlike gastrointestinal carcinoma, strong structural and morphological features are limited and sometimes absent from HCC images. In this study, we describe the classification of HCC images using statistical distributions of features obtained from image analysis of cell nuclei and hepatic trabeculae. Images of 130 hematoxylin-eosin (HE) stained histologic slides were captured at 20X by a slide scanner (Nanozoomer, Hamamatsu Photonics, Japan) and 1112 regions of interest (ROI) images were extracted for classification (551 negatives and 561 positives, including 113 well-differentiated positives). For a single nucleus, the following features were computed: area, perimeter, circularity, ellipticity, long and short axes of elliptic fit, contour complexity and gray level cooccurrence matrix (GLCM) texture features (angular second moment, contrast, homogeneity and entropy). In addition, distributions of nuclear density and hepatic trabecula thickness within an ROI were also extracted. To represent an ROI, statistical distributions (mean, standard deviation and percentiles) of these features were used. In total, 78 features were extracted for each ROI and a support vector machine (SVM) was trained to classify negative and positive ROIs. Experimental results using 5-fold cross validation show 90% sensitivity for an 87.8% specificity. The use of statistical distributions over a relatively large area makes the HCC classifier robust to occasional failures in the extraction of nuclear or hepatic trabecula features, thus providing stability to the system.

  8. Deciphering the Structure and Function of Nuclear Pores Using Single-Molecule Fluorescence Approaches.

    Science.gov (United States)

    Musser, Siegfried M; Grünwald, David

    2016-05-22

    Due to its central role in macromolecular trafficking and nucleocytoplasmic information transfer, the nuclear pore complex (NPC) has been studied in great detail using a wide spectrum of methods. Consequently, many aspects of its architecture, general function, and role in the life cycle of a cell are well understood. Over the last decade, fluorescence microscopy methods have enabled the real-time visualization of single molecules interacting with and transiting through the NPC, allowing novel questions to be examined with nanometer precision. While initial single-molecule studies focused primarily on import pathways using permeabilized cells, it has recently proven feasible to investigate the export of mRNAs in living cells. Single-molecule assays can address questions that are difficult or impossible to answer by other means, yet the complexity of nucleocytoplasmic transport requires that interpretation be based on a firm genetic, biochemical, and structural foundation. Moreover, conceptually simple single-molecule experiments remain technically challenging, particularly with regard to signal intensity, signal-to-noise ratio, and the analysis of noise, stochasticity, and precision. We discuss nuclear transport issues recently addressed by single-molecule microscopy, evaluate the limits of existing assays and data, and identify open questions for future studies. We expect that single-molecule fluorescence approaches will continue to be applied to outstanding nucleocytoplasmic transport questions, and that the approaches developed for NPC studies are extendable to additional complex systems and pathways within cells.

  9. PREFACE: 11th International Spring Seminar on Nuclear Physics: Shell Model and Nuclear Structure - achievements of the past two decades

    Science.gov (United States)

    2015-02-01

    The 11th International Seminar on Nuclear Physics was held in Ischia from May 12 to May 16, 2014. This Seminar was dedicated to Aldo Covello, who has been the promoter of this series of meetings, which started in Sorrento in 1986 and continued with meetings held every two or three years in the Naples area. Aldo's idea was to offer to a group of researchers, actively working in selected fields of Nuclear Physics, the opportunity to confront their points of view in a lively and informal way. The choice for the period of the year, Spring, as well as the sites chosen reflected this intent. The first meeting was of a purely theoretical nature, but it was immediately clear that the scope of these conferences needed to be enlarged calling into play the experimental community. Then, starting from the second meeting, all the following ones have been characterized by fruitful discussion between theoretical and experimental researchers on current achievements and future developments of nuclear structure. This may be read, in fact, as one of the motivating factors for Aldo's election as Fellow of the American Physical Society in 2008 "... for his outstanding contributions to the international nuclear physics community by providing, for over two decades, a venue for theorists and experimentalists to share their latest ideas." The present meeting, organized by Aldo's former students and with the benefit of his suggestions, has maintained this tradition. The title "Shell model and nuclear structure: achievements of the past two decades" recalls that of the 2nd International Spring Seminar "Shell Model and Nuclear Structure: where do we stand?". The main aim of this 11th Seminar was, in fact, to discuss the changes of the past two decades on our view of nuclei in terms of shell structure as well as the perspectives of the shell model, which has been one of the key points in Aldo's research. This point is well accounted by the Opening Speech of Igal Talmi, one of the fathers of the

  10. Improved estimates of the nuclear structure corrections in $\\mu$D

    CERN Document Server

    Hernandez, Oscar Javier; Bacca, Sonia; Dinur, Nir Nevo; Barnea, Nir

    2014-01-01

    We calculate the nuclear structure corrections to the Lamb shift in muonic deuterium by using state-of-the-art nucleon-nucleon potentials derived from chiral effective field theory. Our calculations complement previous theoretical work obtained from phenomenological potentials and the zero range approximation. The study of the chiral convergence order-by-order and the dependence on cutoff variations allows us to improve the estimates on the nuclear structure corrections and the theoretical uncertainty coming from nuclear potentials. This will enter the determination of the nuclear radius from ongoing muonic deuterium experiments at PSI.

  11. Analysis of Challenges for Management Education in India Using Total Interpretive Structural Modelling

    Science.gov (United States)

    Mahajan, Ritika; Agrawal, Rajat; Sharma, Vinay; Nangia, Vinay

    2016-01-01

    Purpose: The purpose of this paper is to identify challenges for management education in India and explain their nature, significance and interrelations using total interpretive structural modelling (TISM), an innovative version of Warfield's interpretive structural modelling (ISM). Design/methodology/approach: The challenges have been drawn from…

  12. Challenge problem and milestones for : Nuclear Energy Advanced Modeling and Simulation (NEAMS) waste Integrated Performance and Safety Codes (IPSC).

    Energy Technology Data Exchange (ETDEWEB)

    Freeze, Geoffrey A.; Wang, Yifeng; Howard, Robert; McNeish, Jerry A.; Schultz, Peter Andrew; Arguello, Jose Guadalupe, Jr.

    2010-09-01

    This report describes the specification of a challenge problem and associated challenge milestones for the Waste Integrated Performance and Safety Codes (IPSC) supporting the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The NEAMS challenge problems are designed to demonstrate proof of concept and progress towards IPSC goals. The goal of the Waste IPSC is to develop an integrated suite of modeling and simulation capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive waste storage or disposal system. The Waste IPSC will provide this simulation capability (1) for a range of disposal concepts, waste form types, engineered repository designs, and geologic settings, (2) for a range of time scales and distances, (3) with appropriate consideration of the inherent uncertainties, and (4) in accordance with robust verification, validation, and software quality requirements. To demonstrate proof of concept and progress towards these goals and requirements, a Waste IPSC challenge problem is specified that includes coupled thermal-hydrologic-chemical-mechanical (THCM) processes that describe (1) the degradation of a borosilicate glass waste form and the corresponding mobilization of radionuclides (i.e., the processes that produce the radionuclide source term), (2) the associated near-field physical and chemical environment for waste emplacement within a salt formation, and (3) radionuclide transport in the near field (i.e., through the engineered components - waste form, waste package, and backfill - and the immediately adjacent salt). The initial details of a set of challenge milestones that collectively comprise the full challenge problem are also specified.

  13. Structure and Activities of Nuclear Medicine in Kuwait.

    Science.gov (United States)

    Elgazzar, Abdelhamid H; Owunwanne, Azuwuike; Alenezi, Saud

    2016-07-01

    The practice of nuclear medicine in Kuwait began in 1965 as a clinic for treating thyroid diseases. The practice developed gradually and until 1981 when the Faculty of Medicine established the Division of Nuclear Medicine in the Department of Radiology, which later became a separate department responsible for establishing and managing the practice in all hospitals of Kuwait. In 1987, a nuclear medicine residency program was begun and it is administered by Kuwait Institute for Medical Specializations originally as a 4-year but currently as a 5-year program. Currently there are 11 departments in the ministry of health hospitals staffed by 49 qualified attending physicians, mostly the diplomats of the Kuwait Institute for Medical Specializations nuclear medicine residency program, 4 academic physicians, 2 radiopharmacists, 2 physicists, and 130 technologists. These departments are equipped with 33 dual-head gamma cameras, 10 SPET/CT, 5 PET/CT, 2 cyclotrons, 1 breast-specific gamma imaging, 1 positron-emitting mammography, 10 thyroid uptake units, 8 technegas machines, 7 PET infusion systems, and 8 treadmills. Activities of nuclear medicine in Kuwait include education and training, clinical service, and research. Education includes nuclear medicine technology program in the Faculty of Allied Health Sciences, the 5-year residency program, medical school teaching distributed among different modules of the integrated curriculum with 14 didactic lecture, and other teaching sessions in nuclear medicine MSc program, which run concurrently with the first part of the residency program. The team of Nuclear Medicine in Kuwait has been active in research and has published more than 300 paper, 11 review articles, 12 book chapters, and 17 books in addition to 36 grants and 2 patents. A PhD program approved by Kuwait University Council would begin in 2016.

  14. Structural basis for the regulation of nuclear import of Epstein-Barr virus nuclear antigen 1 (EBNA1) by phosphorylation of the nuclear localization signal.

    Science.gov (United States)

    Nakada, Ryohei; Hirano, Hidemi; Matsuura, Yoshiyuki

    2017-02-26

    Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) is expressed in every EBV-positive tumor and is essential for the maintenance, replication, and transcription of the EBV genome in the nucleus of host cells. EBNA1 is a serine phosphoprotein, and it has been shown that phosphorylation of S385 in the nuclear localization signal (NLS) of EBNA1 increases the binding affinity to the nuclear import adaptor importin-α1 as well as importin-α5, and stimulates nuclear import of EBNA1. To gain insights into how phosphorylation of the EBNA1 NLS regulates nuclear import, we have determined the crystal structures of two peptide complexes of importin-α1: one with S385-phosphorylated EBNA1 NLS peptide, determined at 2.0 Å resolution, and one with non-phosphorylated EBNA1 NLS peptide, determined at 2.2 Å resolution. The structures show that EBNA1 NLS binds to the major and minor NLS-binding sites of importin-α1, and indicate that the binding affinity of the EBNA1 NLS to the minor NLS-binding site could be enhanced by phosphorylation of S385 through electrostatic interaction between the phosphate group of phospho-S385 and K392 of importin-α1 (corresponding to R395 of importin-α5) on armadillo repeat 8.

  15. Nuclear Dependence in Weak Structure Functions and the Determination of Weak Mixing Angle

    CERN Document Server

    Athar, M Sajjad; Simo, I Ruiz; Vacas, M J Vicente

    2013-01-01

    We have studied nuclear medium effects in the weak structure functions $F^A_2(x)$ and $F^A_3(x)$ and in the extraction of weak mixing angle using Paschos Wolfenstein(PW) relation. We have modified the PW relation for nonisoscalar nuclear target. We have incorporated the medium effects like Pauli blocking, Fermi motion, nuclear binding energy, nucleon correlations, pion $\\&$ rho cloud contributions, and shadowing and antishadowing effects.

  16. Understanding the proton radius puzzle: Nuclear structure effects in light muonic atoms

    Directory of Open Access Journals (Sweden)

    Ji Chen

    2016-01-01

    Full Text Available We present calculations of nuclear structure effects to the Lamb shift in light muonic atoms. We adopt a modern ab-initio approach by combining state-of-the-art nuclear potentials with the hyperspherical harmonics method. Our calculations are instrumental to the determination of nuclear charge radii in the Lamb shift measurements, which will shed light on the proton radius puzzle.

  17. Radioactive nuclear beams and the North American IsoSpin Laboratory (ISL) initiative

    Energy Technology Data Exchange (ETDEWEB)

    Casten, R.F.

    1992-01-01

    Radioactive nuclear beams (RNBs) offer exciting new research opportunities in fields as diverse as nuclear structure, nuclear reactions, astrophysics atomic, materials, and applied science. Their realization in new accelerator complexes also offers important technical challenges. Some of the nuclear physics possibilities afforded by RNBs, with emphasis on low spin nuclear structure, are discussed, accompanied by an outline of the ISL initiative and its status.

  18. Radioactive nuclear beams and the North American IsoSpin Laboratory (ISL) initiative

    Energy Technology Data Exchange (ETDEWEB)

    Casten, R.F.

    1992-12-01

    Radioactive nuclear beams (RNBs) offer exciting new research opportunities in fields as diverse as nuclear structure, nuclear reactions, astrophysics atomic, materials, and applied science. Their realization in new accelerator complexes also offers important technical challenges. Some of the nuclear physics possibilities afforded by RNBs, with emphasis on low spin nuclear structure, are discussed, accompanied by an outline of the ISL initiative and its status.

  19. Have NEC Coat, Will Travel: Structural Basis of Membrane Budding During Nuclear Egress in Herpesviruses.

    Science.gov (United States)

    Bigalke, J M; Heldwein, E E

    2017-01-01

    Herpesviruses are unusual among enveloped viruses because they bud twice yet acquire a single envelope. Furthermore, unlike other DNA viruses that replicate in the nucleus, herpesviruses do not exit it by passing through the nuclear pores or by rupturing the nuclear envelope. Instead, herpesviruses have a complex mechanism of nuclear escape whereby nascent capsids bud at the inner nuclear membrane to form perinuclear virions that subsequently fuse with the outer nuclear membrane, releasing capsids into the cytosol. This makes them some of the very few known viruses that bud into the nuclear envelope. The envelope acquired during nuclear budding does not end up in the mature viral particle but instead allows the capsid to translocate from the nucleus into the cytosol. The viral nuclear egress complex (NEC) is a critical player in the nuclear egress, yet its function and mechanism have remained enigmatic. Recent studies have demonstrated that the NEC buds membranes without the help of other proteins by forming a honeycomb coat, which established the NEC as the first virally encoded budding machine that operates at the nuclear, as opposed to cytoplasmic, membrane. This review discusses our current understanding of the NEC budding mechanism, with the emphasis on studies that illuminated the structure of the NEC coat and its role in capsid budding during herpesvirus nuclear escape.

  20. Structural components of the nuclear body in nuclei of Allium cepa cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nuclear bodies have long been noted in interphase nuclei of plant cells,but their structural component,origin and function are still unclear by now.The present work showed in onion cells the nuclear bodies appeared as a spherical structure about 0.3 to 0.8 μm in diameter.They possibly were formed in nucleolus and subsequently released,and entered into nucleoplasm.Observation through cytochemical staining method at the ultrastructural level confirmed that nuclear bodies consisted of ribonucleoproteins (RNPs) and silver-stainable proteins.Immunocytochemical results revealed that nuclear bodies contained no DNA and ribosomal gene transcription factor (UBF).Based on these data,we suggested that nuclear bodies are not related to the ribosome or other gene transcription activities,instead they may act as subnuclear structures for RNPs transport from nucleolus to cytoplasm,and may also be involved in splicing of pre-mRNAs.

  1. Nuclear shapes: from earliest ideas to multiple shape coexisting structures

    Science.gov (United States)

    Heyde, K.; Wood, J. L.

    2016-08-01

    The concept of the atomic nucleus being characterized by an intrinsic property such as shape came as a result of high precision hyperfine studies in the field of atomic physics, which indicated a non-spherical nuclear charge distribution. Herein, we describe the various steps taken through ingenious experimentation and bold theoretical suggestions that mapped the way for later work in the early 50s by Aage Bohr, Ben Mottelson and James Rainwater. We lay out a long and winding road that marked, in the period of 50s to 70s, the way shell-model and collective-model concepts were reconciled. A rapid increase in both accelerator and detection methods (70s towards the early 2000s) opened new vistas into nuclear shapes, and their coexistence, in various regions of the nuclear mass table. Next, we outline a possible unified view of nuclear shapes: emphasizing decisive steps taken as well as questions remaining, next to the theoretical efforts that could result in an emerging understanding of nuclear shapes, building on the nucleus considered as a strongly interacting system of nucleons as the microscopic starting point.

  2. The effects of nuclear structure on generalized parton distributions of 3He

    CERN Document Server

    Scopetta, S

    2005-01-01

    The effect of the nuclear medium on generalized parton distributions (GPDs) is studied for the 3He nucleus, through a realistic microscopic analysis. In Impulse Approximation, Fermi motion and binding effects, evaluated by modern potentials, are found to be larger than in the forward case and very sensitive to the details of nuclear structure at short distances.

  3. Cardiac nuclear receptors: architects of mitochondrial structure and function.

    Science.gov (United States)

    Vega, Rick B; Kelly, Daniel P

    2017-04-03

    The adult heart is uniquely designed and equipped to provide a continuous supply of energy in the form of ATP to support persistent contractile function. This high-capacity energy transduction system is the result of a remarkable surge in mitochondrial biogenesis and maturation during the fetal-to-adult transition in cardiac development. Substantial evidence indicates that nuclear receptor signaling is integral to dynamic changes in the cardiac mitochondrial phenotype in response to developmental cues, in response to diverse postnatal physiologic conditions, and in disease states such as heart failure. A subset of cardiac-enriched nuclear receptors serve to match mitochondrial fuel preferences and capacity for ATP production with changing energy demands of the heart. In this Review, we describe the role of specific nuclear receptors and their coregulators in the dynamic control of mitochondrial biogenesis and energy metabolism in the normal and diseased heart.

  4. Study of the derivative expansions for the nuclear structure functions

    CERN Document Server

    Simo, I Ruiz

    2008-01-01

    We study the convergence of the series expansions sometimes used in the analysis of the nuclear effects in Deep Inelastic Scattering (DIS) proccesses induced by leptons. The recent advances in statistics and quality of the data, in particular for neutrinos calls for a good control of the theoretical uncertainties of the models used in the analysis. Using realistic nuclear spectral functions which include nucleon correlations, we find that the convergence of the derivative expansions to the full results is poor except at very low values of $x$.

  5. North Korea's nuclear weapons program:verification priorities and new challenges.

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Duk-ho (Korean Consulate General in New York)

    2003-12-01

    A comprehensive settlement of the North Korean nuclear issue may involve military, economic, political, and diplomatic components, many of which will require verification to ensure reciprocal implementation. This paper sets out potential verification methodologies that might address a wide range of objectives. The inspection requirements set by the International Atomic Energy Agency form the foundation, first as defined at the time of the Agreed Framework in 1994, and now as modified by the events since revelation of the North Korean uranium enrichment program in October 2002. In addition, refreezing the reprocessing facility and 5 MWe reactor, taking possession of possible weapons components and destroying weaponization capabilities add many new verification tasks. The paper also considers several measures for the short-term freezing of the North's nuclear weapon program during the process of negotiations, should that process be protracted. New inspection technologies and monitoring tools are applicable to North Korean facilities and may offer improved approaches over those envisioned just a few years ago. These are noted, and potential bilateral and regional verification regimes are examined.

  6. Challenges in Uncertainty and the Science of Nuclear Waste Disposal (Invited)

    Science.gov (United States)

    Alley, W. M.; Alley, R.

    2013-12-01

    Disposal of high-level nuclear waste is a first-of-a-kind endeavor, further saddled by the ambitious goal to achieve containment over periods well beyond human experience. In the United States, as well as other countries, the time period for performance assessment to provide a safety case for deep geologic repositories has gone from 10,000 years in the 1990s to one million years today. Even when the standard was established for 10,000 years, the National Academy of Sciences Board on Radioactive Waste Management warned of the 'scientific trap' set by encouraging the public to expect certainty about repository safety well beyond what science can provide. Paradoxically, the emphasis on predicting repository behavior thousands of centuries into the future stands in stark contrast to a lack of risk assessment of indefinite aboveground storage for the next several generations. We review the uncertainties and technical basis for a geologic repository at Yucca Mountain compared to extended onsite and interim storage. In order to make progress with geologic disposal of nuclear waste, it is important to evaluate any option in the context of the relative merits and limitations of alternative geologic settings, interim storage, and the status quo of extended onsite storage.

  7. Optimizing modulation frequency for structured illumination in a fiber-optic microendoscope to image nuclear morphometry in columnar epithelium.

    Science.gov (United States)

    Keahey, P A; Tkaczyk, T S; Schmeler, K M; Richards-Kortum, R R

    2015-03-01

    Fiber-optic microendoscopes have shown promise to image the changes in nuclear morphometry that accompany the development of precancerous lesions in tissue with squamous epithelium such as in the oral mucosa and cervix. However, fiber-optic microendoscopy image contrast is limited by out-of-focus light generated by scattering within tissue. The scattering coefficient of tissues with columnar epithelium can be greater than that of squamous epithelium resulting in decreased image quality. To address this challenge, we present a small and portable microendoscope system capable of performing optical sectioning using structured illumination (SI) in real-time. Several optical phantoms were developed and used to quantify the sectioning capabilities of the system. Columnar epithelium from cervical tissue specimens was then imaged ex vivo, and we demonstrate that the addition of SI achieves higher image contrast, enabling visualization of nuclear morphology.

  8. Structuring diabetes care in general practices: many improvements, remaining challenges.

    LENUS (Irish Health Repository)

    Jennings, S

    2009-08-07

    BACKGROUND: For people with type 2 diabetes to enjoy improved longevity and quality of life, care needs to be organised in a systematic way. AIM: To test if processes and intermediate outcomes for patients with type 2 diabetes changed with the move to structured care in general practice shared with secondary care. METHODS: An audit of process and intermediate outcomes for patients with type 2 diabetes before and after the change to structured care in 10 Dublin general practices shared with secondary care four years on. RESULTS: Structured diabetes care in general practice has led to more dedicated clinics improved processes of care and increased access to multidisciplinary expertise. Improvement in blood pressure control, the use of aspirin and the use of lipid lowering agents indicate a significant decrease in absolute risk of vascular events for this population. CONCLUSIONS: Structured care in general practice improves intermediate outcomes for people with type 2 diabetes. Further improvements need to be made to reach international targets.

  9. Nuclear structure of light Ca and heavy Cr isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, A.

    2007-07-01

    -energy Coulomb excitation of radioactive beams. Prior to this experiment, the assumption of a sub-shell closure was based only on systematics of excitation energies of the first 2{sup +} states in Cr, Ti, and Ca isotopes. The small B(E2) value for {sup 56}Cr is in agreement with these indications. Further evidence for a N=32 shell gap has meanwhile been found in the development of B(E2) values in Ti isotopes and the evolution of E(4{sup +})/E(2{sup +}) ratios for Cr and Ti. While the experimental evidence has firmly established a sub-shell closure at N=32, calculations are, at present, not able to reproduce the behavior of the B(E2) values, whereas the evolution of excitation energies is well described. Both results touch the limits of present nuclear structure models: in the Cr isotopes, the B(E2) evolution cannot yet be reproduced, and in the Ca isotopes, a consistent picture of mirror energy differences as well as a successful calculation of cross sections are missing. As a result of this work, new experimental data are available for future improvements of such calculations. (orig.)

  10. Nuclear structure studies in JUSTIPEN and EFES activities

    Science.gov (United States)

    Itagaki, Naoyuki

    2009-10-01

    JUSTIPEN: Japan-US Theory Institute for Physics with Exotic Nuclei was launched in June 2006. JUSTIPEN has been established in order to facilitate collaborations between U.S. and Japanese scientists whose main research thrust is in the area of the physics of exotic nuclei. More than 40 nuclear scientists in U.S. have visited Japan in three years, and the many collaborations are established. I briefly summarize the JUSTIPEN activity from the Japanese side. There is counterpart program for the Japanese scientists. International Research Network for Exotic Femto Systems (EFES) was selected as one of the Core-to-Core Programs of Japan Society for the Promotion of Science (JSPS). This is the program to send Japanese nuclear scientists to U.S., Germany, France, Italy, Norway, and Finland and to promote the international collaborations in the field of nuclear study. Many joint workshops were held with partner countries. To operate these international programs, University of Tokyo and RIKEN agreed to corporate with each other and established Todai-RIKEN Joint International Program for Nuclear Physics (TORIJIN) in June 2006. I summarize the activities in three years, and I also mention about the relation between these activities and my personal research -- many-body correlations in light nuclei.

  11. Nuclear Magnetic Resonance Coupling Constants and Electronic Structure in Molecules.

    Science.gov (United States)

    Venanzi, Thomas J.

    1982-01-01

    Theory of nuclear magnetic resonance spin-spin coupling constants and nature of the three types of coupling mechanisms contributing to the overall spin-spin coupling constant are reviewed, including carbon-carbon coupling (neither containing a lone pair of electrons) and carbon-nitrogen coupling (one containing a lone pair of electrons).…

  12. "Parking-garage" structures in nuclear astrophysics and cellular biophysics

    Science.gov (United States)

    Berry, D. K.; Caplan, M. E.; Horowitz, C. J.; Huber, Greg; Schneider, A. S.

    2016-11-01

    A striking shape was recently observed for the endoplasmic reticulum, a cellular organelle consisting of stacked sheets connected by helical ramps [Terasaki et al., Cell 154, 285 (2013), 10.1016/j.cell.2013.06.031]. This shape is interesting both for its biological function, to synthesize proteins using an increased surface area for ribosome factories, and its geometric properties that may be insensitive to details of the microscopic interactions. In the present work, we find very similar shapes in our molecular dynamics simulations of the nuclear pasta phases of dense nuclear matter that are expected deep in the crust of neutron stars. There are dramatic differences between nuclear pasta and terrestrial cell biology. Nuclear pasta is 14 orders of magnitude denser than the aqueous environs of the cell nucleus and involves strong interactions between protons and neutrons, while cellular-scale biology is dominated by the entropy of water and complex assemblies of biomolecules. Nonetheless, the very similar geometry suggests both systems may have similar coarse-grained dynamics and that the shapes are indeed determined by geometrical considerations, independent of microscopic details. Many of our simulations self-assemble into flat sheets connected by helical ramps. These ramps may impact the thermal and electrical conductivities, viscosity, shear modulus, and breaking strain of neutron star crust. The interaction we use, with Coulomb frustration, may provide a simple model system that reproduces many biologically important shapes.

  13. Cleave to Leave : Structural Insights into the Dynamic Organization of the Nuclear Pore Complex

    NARCIS (Netherlands)

    Dokudovskaya, Svetlana; Veenhoff, Liesbeth M.; Rout, Michael P.

    2002-01-01

    A detailed understanding of the fine structure of the nuclear pore complex has remained elusive. Now, studies on a small protein domain have shed light on the dynamic organization of this massive assembly.

  14. Mechanistic Insights from Structural Analyses of Ran-GTPase-Driven Nuclear Export of Proteins and RNAs.

    Science.gov (United States)

    Matsuura, Yoshiyuki

    2016-05-22

    Understanding how macromolecules are rapidly exchanged between the nucleus and the cytoplasm through nuclear pore complexes is a fundamental problem in biology. Exportins are Ran-GTPase-dependent nuclear transport factors that belong to the karyopherin-β family and mediate nuclear export of a plethora of proteins and RNAs, except for bulk mRNA nuclear export. Exportins bind cargo macromolecules in a Ran-GTP-dependent manner in the nucleus, forming exportin-cargo-Ran-GTP complexes (nuclear export complexes). Transient weak interactions between exportins and nucleoporins containing characteristic FG (phenylalanine-glycine) repeat motifs facilitate nuclear pore complex passage of nuclear export complexes. In the cytoplasm, nuclear export complexes are disassembled, thereby releasing the cargo. GTP hydrolysis by Ran promoted in the cytoplasm makes the disassembly reaction virtually irreversible and provides thermodynamic driving force for the overall export reaction. In the past decade, X-ray crystallography of some of the exportins in various functional states coupled with functional analyses, single-particle electron microscopy, molecular dynamics simulations, and small-angle solution X-ray scattering has provided rich insights into the mechanism of cargo binding and release and also begins to elucidate how exportins interact with the FG repeat motifs. The knowledge gained from structural analyses of nuclear export is being translated into development of clinically useful inhibitors of nuclear export to treat human diseases such as cancer and influenza.

  15. Biophysics and Structure to Counter Threats and Challenges

    CERN Document Server

    Margaris, Manolia

    2013-01-01

    This ASI brought together a diverse group of experts who span virology, biology, biophysics, chemistry, physics and engineering.  Prominent lecturers representing world renowned scientists from nine (9) different countries, and students from around the world representing eighteen (18) countries, participated in the ASI organized by Professors Joseph Puglisi (Stanford University, USA) and Alexander Arseniev (Moscow, RU).   The central hypothesis underlying this ASI was that interdisciplinary research, merging principles of physics, chemistry and biology, can drive new discovery in detecting and fighting chemical and bioterrorism agents, lead to cleaner environments and improved energy sources, and help propel development in NATO partner countries.  At the end of the ASI students had an appreciation of how to apply each technique to their own particular research problem and to demonstrate that multifaceted approaches and new technologies are needed to solve the biological challenges of our time.  The course...

  16. Co-ordination of the International Network of Nuclear Structure and Decay Data Evaluators

    Energy Technology Data Exchange (ETDEWEB)

    Ricard-McCutchan, E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Dimitriou, P. [Intl Atomic Energy Agency (IAEA), Vienna (Austria); Nichols, A. L. [Univ. of Surrey, Guildford (United Kingdom)

    2015-08-01

    The 21st meeting of the International Network of Nuclear Structure and Decay Data Evaluators was convened at the IAEA Headquarters, Vienna, from 20 to 24 April 2015 under the auspices of the IAEA Nuclear Data Section. This meeting was attended by 36 scientists from 15 Member States, plus IAEA staff, concerned with the compilation, evaluation and dissemination of nuclear structure and decay data. A summary of the meeting, data centre reports, various proposals considered, and actions agreed by the participants, as well as recommendations/conclusions are presented within this document.

  17. Development of the NPL gamma-ray spectrometer NANA for traceable nuclear decay and structure studies.

    Science.gov (United States)

    Lorusso, G; Shearman, R; Regan, P H; Judge, S M; Bell, S; Collins, S M; Larijani, C; Ivanov, P; Jerome, S M; Keightley, J D; Lalkovski, S; Pearce, A K; Podolyak, Zs

    2016-03-01

    We present a brief report on the progress towards the construction of the National Nuclear Array (NANA), a gamma-ray coincidence spectrometer for discrete-line nuclear structure and decay measurements. The proposed spectrometer will combine a gamma-ray energy resolution of approximately 3% at 1MeV with sub-nanosecond timing discrimination between successive gamma rays in mutually coincident decay cascades. We also review a number of recent measurements using coincidence fast-timing gamma-ray spectroscopy for nuclear structure studies, which have helped to inform the design criteria for the NANA spectrometer.

  18. Structural Equations and Causal Explanations: Some Challenges for Causal SEM

    Science.gov (United States)

    Markus, Keith A.

    2010-01-01

    One common application of structural equation modeling (SEM) involves expressing and empirically investigating causal explanations. Nonetheless, several aspects of causal explanation that have an impact on behavioral science methodology remain poorly understood. It remains unclear whether applications of SEM should attempt to provide complete…

  19. Implementing Structured English Immersion in Arizona: Benefits, Challenges, and Opportunities

    Science.gov (United States)

    Rios-Aguilar, Cecilia; Gonzalez Canche, Manuel S.; Moll, Luis C.

    2012-01-01

    Background/Context: Arizona's most recent English Language Learner (ELL) legislation, starting in the school year 2008-2009, requires all such students be educated through a specific Structured English Immersion (SEI) model: the 4-hour English Language Development (ELD) block. The basic premise behind this particular model is that ELL students…

  20. Current Understanding and Remaining Challenges in Modeling Long-Term Degradation of Borosilicate Nuclear Waste Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Vienna, John D. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Ryan, Joseph V. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Gin, Stephane [CEA Marcoule, DTCD SECM, Bagnols-sur-Ceze (France); Inagaki, Yaohiro [Dept. of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoda (Japan)

    2013-12-01

    Chemical durability is not a single material property that can be uniquely measured. Instead it is the response to a host of coupled material and environmental processes whose rates are estimated by a combination of theory, experiment, and modeling. High-level nuclear waste (HLW) glass is perhaps the most studied of any material yet there remain significant technical gaps regarding their chemical durability. The phenomena affecting the long-term performance of HLW glasses in their disposal environment include surface reactions, transport properties to and from the reacting glass surface, and ion exchange between the solid glass and the surrounding solution and alteration products. The rates of these processes are strongly influenced and are coupled through the solution chemistry, which is in turn influenced by the reacting glass and also by reaction with the near-field materials and precipitation of alteration products. Therefore, those processes must be understood sufficiently well to estimate or bound the performance of HLW glass in its disposal environment over geologic time-scales. This article summarizes the current state of understanding of surface reactions, transport properties, and ion exchange along with the near-field materials and alteration products influences on solution chemistry and glass reaction rates. Also summarized are the remaining technical gaps along with recommended approaches to fill those technical gaps.

  1. Challenges of deflecting an asteroid or cometary nucleus with a nuclear burst

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Paul A [Los Alamos National Laboratory; Plesko, Cathy S [Los Alamos National Laboratory; Clement, Ryan R C [Los Alamos National Laboratory; Conlon, Leann M [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Guzik, Joyce A [Los Alamos National Laboratory; Pritchett - Sheets, Lori A [Los Alamos National Laboratory; Huebner, Walter F [SOUTHWEST RESEARCH INSTITUTE

    2009-01-01

    There are many natural disasters that humanity has to deal with over time. These include earthquakes, tsunami, hurricanes, floods, asteroid strikes, and so on. Many of these disasters occur slowly enough that some advance warning of which areas will be affected is possible. However, in almost all cases, the response is to evacuate the area to be affected and deal with the damage later. The evacuations for hurricanes Katrina and Rita on the US Gulf Coast in 2005 demonstrated the chaos that can result. In contrast with other natural disasters. it is likely that an asteroid or cometary nucleus on a collision course with Earth is likely to be detected with enough warning time to possibly deflect it away from the collision course. Thanks to near-Earth object (NEO) surveys, people are working towards a goal of cataloging at least 90% of all near-Earth objects with diameters larger than {approx}140 meters in the next decade. The question is how to mitigate the threat from an asteroid or cometary nucleus found to be on a collision course. We briefly review some possible methods, describing their good and bad points, and then embark on a more detailed description of using a nuclear munition in standoff mode to deflect an asteroid or cometary nucleus before it can hit Earth.

  2. Challenges of deflecting an asteroid or comet nucleus with a nuclear burst

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, Paul A [Los Alamos National Laboratory; Plesko, Cathy S [Los Alamos National Laboratory; Clement, Ryan R. C. [Los Alamos National Laboratory; Conlon, Le Ann M [Los Alamos National Laboratory; Weaver, Robert P [Los Alamos National Laboratory; Guzik, Joyce A [Los Alamos National Laboratory; Pritchett - Sheets, Lori A [Los Alamos National Laboratory; Huebner, Walter F [SWRI

    2009-01-01

    There are many natural disasters that humanity has to deal with over time. These include earthquakes, tsunamis, hurricanes, floods, asteroid strikes, and so on. Some of these disasters occur slowly enough that some advance warning is possible for affected areas. In this case, the response is to evacuate the affected area and deal wilh the damage later. The Katrina and Rita hurricane evacuations on the U.S. Gulf Coasl in 2005 demonstrated the chaos that can result from such a response. In contrast with other natural disasters, it is likely that an asteroid or comet nucleus on a collision course with Earth will be detected with enough warning time to possibly deflect it away. Thanks to Near-Earth Object (NED) surveys, people are working towards a goal of cataloging at least 90% of all near-Earth objects with diameters larger than {approx} 140 meters in the next fifteen years. The important question then, is how to mitigate the threat from an asteroid or comet nucleus found to be on a collision course with Earth. In this paper. we briefly review some possible deflection methods, describe their good and bad points, and then embark on a more detailed description of using nuclear munitions in a standoff mode to deflect the asteroid or comet nucleus before it can hit Earth.

  3. The challenge of preparation for a chemical, biological, radiological or nuclear terrorist attack

    Directory of Open Access Journals (Sweden)

    Alexander David

    2006-01-01

    Full Text Available Terrorism is not a new phenomenon, but, in the contemporary scene, it has established itself in a manner which commands the most serious attention of the authorities. Until relatively recently, the major threat has been through the medium of conventional weaponry and explosives. Their obvious convenience of use and accessibility guarantees that such methods will continue to represent a serious threat. However, over the last few years, terrorists have displayed an enthusiasm for higher levels of carnage, destruction and publicity. This trend leads inexorably to the conclusion that chemical, biological, radiological and nuclear (CBRN methods will be pursued by terrorist organisations, particularly those which are well organised, are based on immutable ideological principles, and have significant financial backing. Whilst it is important that the authorities and the general public do not risk over-reacting to such a threat (otherwise, they will do the work of the terrorists for them, it would be equally ill-advised to seek comfort in denial. The reality of a CBRN event has to be accepted and, as a consequence, the authorities need to consider (and take seriously how individuals and the community are likely to react thereto and to identify (and rehearse in a realistic climate what steps would need to be taken to ameliorate the effects of such an event.

  4. Nuclear imaging of neuroinflammation: a comprehensive review of [{sup 11}C]PK11195 challengers

    Energy Technology Data Exchange (ETDEWEB)

    Chauveau, Fabien; Camp, Nadja van; Tavitian, Bertrand [Service Hospitalier Frederic Joliot, Laboratoire d' Imagerie Moleculaire Experimentale, CEA, Institut d' Imagerie BioMedicale, Orsay (France); INSERM, U803, Orsay (France); Boutin, Herve [University of Manchester, Faculty of Life Sciences, Manchester (United Kingdom); Dolle, Frederic [Service Hospitalier Frederic Joliot, Laboratoire d' Imagerie Moleculaire Experimentale, CEA, Institut d' Imagerie BioMedicale, Orsay (France)

    2008-12-15

    Neurodegenerative, inflammatory and neoplastic brain disorders involve neuroinflammatory reactions, and a biomarker of neuroinflammation would be useful for diagnostic, drug development and therapy control of these frequent diseases. In vivo imaging can document the expression of the peripheral benzodiazepine receptor (PBR)/translocator protein 18 kDa (TSPO) that is linked to microglial activation and considered a hallmark of neuroinflammation. The prototype positron emission tomography tracer for PBR, [{sup 11}C]PK11195, has shown limitations that until now have slowed the clinical applications of PBR imaging. In recent years, dozens of new PET and SPECT radioligands for the PBR have been radiolabelled, and several have been evaluated in imaging protocols. Here we review the new PBR ligands proposed as challengers of [{sup 11}C]PK11195, critically analyze preclinical imaging studies and discuss their potential as neuroinflammation imaging agents. (orig.)

  5. Spin-dependent structure functions in nuclear matter and the polarized EMC effect.

    Science.gov (United States)

    Cloët, I C; Bentz, W; Thomas, A W

    2005-07-29

    An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu--Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F2N(A)/F2N ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g1p(A), we find that the ratio g1p(A)/g1p differs significantly from unity, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which, if confirmed experimentally, will reveal much about the quark structure of nuclear matter.

  6. THE AIMS AND ACTIVITIES OF THE INTERNATIONAL NETWORK OF NUCLEAR STRUCTURE AND DECAY DATA EVALUATORS.

    Energy Technology Data Exchange (ETDEWEB)

    NICHOLS,A.L.; TULI, J.K.

    2007-04-22

    International Network of Nuclear Structure and Decay Data (NSDD) Evaluators consists of a number of evaluation groups and data service centers in several countries that appreciate the merits of working together to maintain and ensure the quality and comprehensive content of the ENSDF database (Evaluated Nuclear Structure Data File). Biennial meetings of the network are held under the auspices of the International Atomic Energy Agency (IAEA) to assign evaluation responsibilities, monitor progress, discuss improvements and emerging difficulties, and agree on actions to be undertaken by individual members. The evaluated data and bibliographic details are made available to users via various media, such as the journals ''Nuclear Physics A'' and ''Nuclear Data Sheets'', the World Wide Web, on CD-ROM, wall charts of the nuclides and ''Nuclear Wallet Cards''. While the ENSDF master database is maintained by the US National Nuclear Data Center at the Brookhaven National Laboratory, these data are also available from other nuclear data centers including the IAEA Nuclear Data Section. The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy, in cooperation with the IAEA, organizes workshops on NSDD at regular intervals. The primary aims of these particular workshops are to provide hands-on training in the data evaluation processes, and to encourage new evaluators to participate in NSDD activities. The technical contents of these NSDD workshops are described, along with the rationale for the inclusion of various topics.

  7. Challenges to quantum chromodynamics: Anomalous spin, heavy quark, and nuclear phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J.

    1989-11-01

    The general structure of QCD meshes remarkably well with the facts of the hadronic world, especially quark-based spectroscopy, current algebra, the approximate point-like structure of large momentum transfer inclusive reactions, and the logarithmic violation of scale invariance in deep inelastic lepton-hadron reactions. QCD has been successful in predicting the features of electron-positron and photon-photon annihilation into hadrons, including the magnitude and scaling of the cross sections, the shape of the photon structure function, the production of hadronic jets with patterns conforming to elementary quark and gluon subprocesses. The experimental measurements appear to be consistent with basic postulates of QCD, that the charge and weak currents within hadrons are carried by fractionally-charged quarks, and that the strength of the interactions between the quarks, and gluons becomes weak at short distances, consistent with asymptotic freedom. Nevertheless in some cases, the predictions of QCD appear to be in dramatic conflict with experiment. The anomalies suggest that the proton itself as a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrival proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trival oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non- negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. 144 refs., 46 figs., 2 tabs.

  8. Alkali Metal Rankine Cycle Boiler Technology Challenges and Some Potential Solutions for Space Nuclear Power and Propulsion Applications

    Science.gov (United States)

    Stone, James R.

    1994-01-01

    Alkali metal boilers are of interest for application to future space Rankine cycle power conversion systems. Significant progress on such boilers was accomplished in the 1960's and early 1970's, but development was not continued to operational systems since NASA's plans for future space missions were drastically curtailed in the early 1970's. In particular, piloted Mars missions were indefinitely deferred. With the announcement of the Space Exploration Initiative (SEI) in July 1989 by President Bush, interest was rekindled in challenging space missions and, consequently in space nuclear power and propulsion. Nuclear electric propulsion (NEP) and nuclear thermal propulsion (NTP) were proposed for interplanetary space vehicles, particularly for Mars missions. The potassium Rankine power conversion cycle became of interest to provide electric power for NEP vehicles and for 'dual-mode' NTP vehicles, where the same reactor could be used directly for propulsion and (with an additional coolant loop) for power. Although the boiler is not a major contributor to system mass, it is of critical importance because of its interaction with the rest of the power conversion system; it can cause problems for other components such as excess liquid droplets entering the turbine, thereby reducing its life, or more critically, it can drive instabilities-some severe enough to cause system failure. Funding for the SEI and its associated technology program from 1990 to 1993 was not sufficient to support significant new work on Rankine cycle boilers for space applications. In Fiscal Year 1994, funding for these challenging missions and technologies has again been curtailed, and planning for the future is very uncertain. The purpose of this paper is to review the technologies developed in the 1960's and 1970's in the light of the recent SEI applications. In this way, future Rankine cycle boiler programs may be conducted most efficiently. This report is aimed at evaluating alkali metal boiler

  9. Data structure and software engineering challenges and improvements

    CERN Document Server

    Antonakos, James L

    2011-01-01

    Data structure and software engineering is an integral part of computer science. This volume presents new approaches and methods to knowledge sharing, brain mapping, data integration, and data storage. The author describes how to manage an organization's business process and domain data and presents new software and hardware testing methods. The book introduces a game development framework used as a learning aid in a software engineering at the university level. It also features a review of social software engineering metrics and methods for processing business information. It explains how to

  10. Cost - The challenge for advanced materials and structures

    Science.gov (United States)

    Davis, John G., Jr.; Freeman, William T., Jr.; Siddiqi, Shahid

    1992-01-01

    Information is presented on the cost of various aircraft structures, together with methods for predicting and reducing cost. The need for the development of cost models, and of a comparative cost algorithm which could function as an engineering design tool to evaluate different design concepts, is emphasized. Efforts are underway to develop cost models that establish building-block unit cell elements that represent different material forms, geometric shapes, fabrication processes, and methods of assembly, with the purpose of expressing cost per pound or labor per pound data, with physical design and manufacture variables that a designer can visualize.

  11. Structural Aging Program to evaluate continued performance of safety-related concrete structures in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Naus, D.J.; Oland, C.B. [Oak Ridge National Lab., TN (United States); Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States)

    1994-03-01

    This report discusses the Structural Aging (SAG) Program which is being conducted at the Oak Ridge National Laboratory (ORNL) for the United States Nuclear Regulatory commission (USNRC). The SAG Program is addressing the aging management of safety-related concrete structures in nuclear power plants for the purpose of providing improved technical bases for their continued service. The program is organized into three technical tasks: Materials Property Data Base, Structural Component Assessment/Repair Technologies, and Quantitative Methodology for continued Service Determinations. Objectives and a summary of recent accomplishments under each of these tasks are presented.

  12. Spectral Structure of Electron Antineutrinos from Nuclear Reactors

    CERN Document Server

    Dwyer, D A

    2014-01-01

    Recent measurements of the positron energy spectrum obtained from inverse beta decay interactions of reactor electron antineutrinos show an excess in the 4 to 6 MeV region relative to current predictions. First-principle calculations of fission and beta decay processes within a typical pressurized water reactor core identify prominent fission daughter isotopes as a possible origin for this excess. These calculations also predict percent-level substructure in the antineutrino spectrum due to Coulomb effects in beta decay. Precise measurement of this substructure can constrain nuclear reactor physics. The substructure can be a systematic uncertainty for measurements utilizing the detailed spectral shape.

  13. Spectral structure of electron antineutrinos from nuclear reactors.

    Science.gov (United States)

    Dwyer, D A; Langford, T J

    2015-01-01

    Recent measurements of the positron energy spectrum obtained from inverse beta decay interactions of reactor electron antineutrinos show an excess in the 4 to 6 MeV region relative to current predictions. First-principles calculations of fission and beta decay processes within a typical pressurized water reactor core identify prominent fission daughter isotopes as a possible origin for this excess. These calculations also predict percent-level substructures in the antineutrino spectrum due to Coulomb effects in beta decay. Precise measurement of these substructures can elucidate the nuclear processes occurring within reactors. These substructures can be a systematic issue for measurements utilizing the detailed spectral shape.

  14. Alternative similarity renormalization group generators in nuclear structure calculations

    CERN Document Server

    Dicaire, Nuiok M; Navratil, Petr

    2014-01-01

    The similarity renormalization group (SRG) has been successfully applied to soften interactions for ab initio nuclear calculations. In almost all practical applications in nuclear physics, an SRG generator with the kinetic energy operator is used. With this choice, a fast convergence of many-body calculations can be achieved, but at the same time substantial three-body interactions are induced even if one starts from a purely two-nucleon (NN) Hamiltonian. Three-nucleon (3N) interactions can be handled by modern many-body methods. However, it has been observed that when including initial chiral 3N forces in the Hamiltonian, the SRG transformations induce a non-negligible four-nucleon interaction that cannot be currently included in the calculations for technical reasons. Consequently, it is essential to investigate alternative SRG generators that might suppress the induction of many-body forces while at the same time might preserve the good convergence. In this work we test two alternative generators with oper...

  15. Nuclear Structure aspects of gamma decay from giant resonances

    Directory of Open Access Journals (Sweden)

    Bracco A.

    2014-01-01

    Full Text Available The gamma decay of the giant dipole resonance (including its tail region is an important tool to probe the properties of these states, and thus to test the predictions of mean field theories. This paper focuses on two main aspects concerning the electric dipole excitation in nuclei. These are the study of the isospin character of the low energy tail of the Giant Dipole Resonance (GDR, the so-called Pygmy resonance, and the isospin mixing of nuclear systems at finite temperature. In the first case, the Pygmy resonance has been populated in the inelastic scattering reaction 17O+124Sn at 20 MeV/u. Its gamma decay has been measured using the AGATA Demonstrator and an array of 8 large volume LaBr3:Ce scintillators. In the second case, the gamma decay of the GDR in thermalized nuclear systems, formed in fusion evaporation reactions, has been used to investigate the isospin mixing in 80Zr. For this work the reactions 40Ca+40Ca at 3.4 MeV/u and 37Cl +44Ca at 2.6 MeV/u were used.

  16. Tox21Challenge to build predictive models of nuclear receptor and stress response pathways as mediated by exposure to environmental chemicals and drugs

    Directory of Open Access Journals (Sweden)

    Ruili eHuang

    2016-01-01

    Full Text Available Tens of thousands of chemicals with poorly understood biological properties are released into the environment each day. High-throughput screening (HTS is potentially a more efficient and cost-effective alternative to traditional toxicity tests. Using HTS, one can profile chemicals for potential adverse effects and prioritize a manageable number for more in-depth testing. Importantly, it can provide clues to mechanism of toxicity. The Tox21 program has generated >50 million quantitative high-throughput screening (qHTS data points. A library of several thousands of compounds, including environmental chemicals and drugs, is screened against a panel of nuclear receptor and stress response pathway assays. The National Center for Advancing Translational Sciences (NCATS has organized an International data challenge in order to crowd-source data and build predictive toxicity models. This Challenge asks a crowd of researchers to use these data to elucidate the extent to which the interference of biochemical and cellular pathways by compounds can be inferred from chemical structure data. The data generated against the Tox21 library served as the training set for this modeling Challenge. The competition attracted participants from 18 different countries to develop computational models aimed at better predicting chemical toxicity. The winning models from nearly 400 model submissions all achieved >80% accuracy. Several models exceeded 90% accuracy, which was measured by area under the receiver operating characteristic curve (AUC-ROC. Combining the winning models with the knowledge already gained from Tox21 screening data are expected to improve the community’s ability to prioritize novel chemicals with respect to potential human health concern.

  17. Off-shell Corrections and Moments of the Deep Inelastic Nuclear Structure Functions

    CERN Document Server

    Cothran, C D; Liuti, S

    1998-01-01

    We present an improved method for handling off-shell effects in deep inelastic nuclear scattering. With a firm understanding of the effects of the nuclear wave function, including these off-shell corrections as well as binding and nucleon-nucleon correlations, we can begin to examine the role of QCD in nuclei through an analysis of the moments of the nuclear structure function. Our analysis is aimed at extracting the Q^2 dependence of the moments of the nucleon structure function by using the recent high x world Iron data and by properly removing nuclear effects from the perturbative contribution. In addition, we compare quantitatively the behavior of the extracted moments with a simple O(1/Q^2) phenomenological form and we determine the mass term for this parametrization.

  18. DETERMINING THE EFFECTS OF RADIATION ON AGING CONCRETE STRUCTURES OF NUCLEAR REACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Serrato, M.

    2010-01-29

    The U.S. Department of Energy Office of Environmental Management (DOE-EM) is responsible for the Decontamination and Decommissioning (D&D) of nuclear facilities throughout the DOE Complex. Some of these facilities will be completely dismantled, while others will be partially dismantled and the remaining structure will be stabilized with cementitious fill materials. The latter is a process known as In-Situ Decommissioning (ISD). The ISD decision process requires a detailed understanding of the existing facility conditions, and operational history. System information and material properties are need for aged nuclear facilities. This literature review investigated the properties of aged concrete structures affected by radiation. In particular, this review addresses the Savannah River Site (SRS) isotope production nuclear reactors. The concrete in the reactors at SRS was not seriously damaged by the levels of radiation exposure. Loss of composite compressive strength was the most common effect of radiation induced damage documented at nuclear power plants.

  19. Making nuclear waste governable. Deep underground disposal and the challenge of reversibility

    Energy Technology Data Exchange (ETDEWEB)

    Gonnot, Francois-Michel; Dupuis, Marie-Claude; Aparicio, Luis (ed.) [Agence nationale pour la gestion des dechets radioactifs - Andra, 1-7, rue Jean-Monnet, 92298 Chatenay-Malabry cedex (France); Barthe, Yannick [Centre de Sociologie de l' Innovation, Mines Paris Tech, 60, Boulevard Saint-Michel 75272 Paris cedex 06 (France); Cezanne-Bert, Pierrick; Chateauraynaud, Francis [Groupe de Sociologie Pragmatique et Reflexive - GSPR, Ecole des hautes etudes en sciences sociales - EHESS, 105 bd Raspail 75006 Paris (France)

    2010-12-15

    This book is the result of a collaboration that began over two years ago between researchers from the social sciences and ANDRA engineers and natural scientists. Contributions to the various chapters have been discussed and enhanced, especially during the workshop and the interdisciplinary conference both held by ANDRA in 2008 and 2009 respectively. The French approach to reversibility will also once again be developed and open to debate during the international conference organised under the aegis of the OECD's Nuclear Energy Agency in Reims from December 14 to 17, 2010. Devoted to the application of the reversibility principle to radioactive waste management, this work is divided into three chapters. The discussion throughout the chapters deals mainly with the issue of how to implement the 'definitive securing' of the waste, as stated by the French Planning Act dated June 28 2006, while providing a flexible management programme that keeps options open over time to make radioactive waste governable. The originality of this work is, precisely, to focus on the specific operational provisions being considered today to allow present and future generations to ensuring the protection of persons and the environment sustainably. The first chapter was written by Yannick Barthe, researcher at the CNRS and member of the Centre for the Sociology of Innovation at the Mines ParisTech School. He examines the political qualities of technology, analysing the action modes related to the various management solutions being suggested. According to the author, different decision-making models - as well as specific approaches to safety - are inscribed within technical devices. In this regard, the introduction of the reversibility principle appears to be a radical innovation, both in technical and in political terms. The second chapter reports on Andra's current positioning with respect to the project of a reversible deep disposal facility. It presents a recursive

  20. Changing nuclear landscape and unique PML structures during early epigenetic transitions of human embryonic stem cells.

    Science.gov (United States)

    Butler, John T; Hall, Lisa L; Smith, Kelly P; Lawrence, Jeanne B

    2009-07-01

    The complex nuclear structure of somatic cells is important to epigenomic regulation, yet little is known about nuclear organization of human embryonic stem cells (hESC). Here we surveyed several nuclear structures in pluripotent and transitioning hESC. Observations of centromeres, telomeres, SC35 speckles, Cajal Bodies, lamin A/C and emerin, nuclear shape and size demonstrate a very different "nuclear landscape" in hESC. This landscape is remodeled during a brief transitional window, concomitant with or just prior to differentiation onset. Notably, hESC initially contain abundant signal for spliceosome assembly factor, SC35, but lack discrete SC35 domains; these form as cells begin to specialize, likely reflecting cell-type specific genomic organization. Concomitantly, nuclear size increases and shape changes as lamin A/C and emerin incorporate into the lamina. During this brief window, hESC exhibit dramatically different PML-defined structures, which in somatic cells are linked to gene regulation and cancer. Unlike the numerous, spherical somatic PML bodies, hES cells often display approximately 1-3 large PML structures of two morphological types: long linear "rods" or elaborate "rosettes", which lack substantial SUMO-1, Daxx, and Sp100. These occur primarily between Day 0-2 of differentiation and become rare thereafter. PML rods may be "taut" between other structures, such as centromeres, but clearly show some relationship with the lamina, where PML often abuts or fills a "gap" in early lamin A/C staining. Findings demonstrate that pluripotent hES cells have a markedly different overall nuclear architecture, remodeling of which is linked to early epigenomic programming and involves formation of unique PML-defined structures.

  1. A study of nuclear effect in $F_3$ structure function in the deep inelastic $\

    CERN Document Server

    Athar, M Sajjad; Singh, S K; Vacas, M J Vicente

    2009-01-01

    We study nuclear effect in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by taking into account Fermi motion, binding, target mass correction, shadowing and anti-shadowing corrections. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. Results for $F^A_3(x)$ have been compared with the results reported at NuTeV and also with some of the older experiments reported in the literature.

  2. Laminopathies: involvement of structural nuclear proteins in the pathogenesis of an increasing number of human diseases.

    Science.gov (United States)

    Maraldi, Nadir M; Squarzoni, Stefano; Sabatelli, Patrizia; Capanni, Cristina; Mattioli, Elisabetta; Ognibene, Andrea; Lattanzi, Giovanna

    2005-05-01

    Just at the beginning of the millennium the neologism laminopathies has been introduced in the scientific vocabulary. An exponential increase of interest on the subject started concomitantly, so that a formerly quite neglected group of rare human diseases is now widely investigated. This review will cover the history of the identification of the molecular basis for fourteen (since now) hereditary diseases arising from defects in genes that encode nuclear envelope and nuclear lamina-associated proteins and will also consider the hypotheses that can account for the role of structural nuclear proteins in the pathogenesis of diseases affecting a wide spectrum of tissues.

  3. Precision mass measurements of short-lived nuclides for nuclear structure studies at TITAN

    Directory of Open Access Journals (Sweden)

    Chaudhuri A.

    2014-03-01

    Full Text Available TITAN (TRIUMF’s Ion Trap for Atomic and Nuclear science at TRIUMF’s rare isotope beam facility ISAC is an advanced Penning trap based mass spectrometer dedicated to precise and accurate mass determinations. An overview of TITAN, the measurement technique and a highlight of recent mass measurements of the short-lived nuclides important to the nuclear structure program at TITAN are presented.

  4. Nuclear structure at high spin using multidetector gamma array and ancillary detectors

    Indian Academy of Sciences (India)

    S Muralithar

    2014-04-01

    A multidetector gamma array (GDA), for studying nuclear structure was built with ancillary devices namely gamma multiplicity filter and charged particle detector array. This facility was designed for in-beam gamma spectroscopy measurements in fusion evaporation reactions at Inter-University Accelerator Centre, New Delhi. Description of the facility and in-beam performance with two experimental studies done are presented. This array was used in a number of nuclear spectroscopic and reaction investigations.

  5. Regulatory Issues and Challenges in Developing Seismic Source Characterizations for New Nuclear Power Plant Applications in the US

    Science.gov (United States)

    Fuller, C. W.; Unruh, J.; Lindvall, S.; Lettis, W.

    2009-05-01

    An integral component of the safety analysis for proposed nuclear power plants within the US is a probabilistic seismic hazard assessment (PSHA). Most applications currently under NRC review followed guidance provided within NRC Regulatory Guide 1.208 (RG 1.208) for developing seismic source characterizations (SSC) for their PSHA. Three key components of RG 1.208 guidance is that applicants should: (1) use existing PSHA models and SSCs accepted by the NRC as SSC as a starting point for their SSCs; (2) evaluate new information and data developed since acceptance of the starting model to determine if the model should be updated; and (3) follow guidelines set forth by the Senior Seismic Hazard Analysis Committee (SSHAC) (NUREG/CR-6372) in developing significant updates (i.e., updates should capture SSC uncertainty through representing the "center, body, and range of technical interpretations" of the informed technical community). Major motivations for following this guidance are to ensure accurate representations of hazard and regulatory stability in hazard estimates for nuclear power plants. All current applications with the NRC have used the EPRI-SOG source characterizations developed in the 1980s as their starting point model, and all applicants have followed RG 1.208 guidance in updating the EPRI- SOG model. However, there has been considerable variability in how applicants have interpreted the guidance, and thus there has been considerable variability in the methodology used in updating the SSCs. Much of the variability can be attributed to how different applicants have interpreted the implications of new data, new interpretations of new and/or old data, and new "opinions" of members of the informed technical community. For example, many applicants and the NRC have wrestled with the challenge of whether or not to update SSCs in light of new opinions or interpretations of older data put forth by one member of the technical community. This challenge has been

  6. Challenges for the nuclear safety of the deregulation of electricity markets; Defis pour la surete nucleaire de la dereglementation des marches de l'electricite

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    Eurosafe 2000 was organised around two round tables on the first day and four seminars on the second day. The first round table dealt with general aspects of deregulation including the economic constraints and the special challenges arising during transition from regulated to deregulated structures. The second round table focussed on technical and organisational safety issues which are directly or indirectly related to the changes introduced by deregulation. The four seminars hold in order to provide opportunities for comparing experiences and learning about recent activities of IPSN, GRS and their partners in the European Union and Eastern Europe: Seminar 1 (Nuclear installation safety, assessment and analysis): assessment of the flooding incident at the Blayais nuclear power plant; PSA data base, comparison of the French and German approach; assessment of the Balakovo fire probabilistic study and elaboration of a guide for reviewing fire PSA; comprehensive technical assessment of an advanced German PWR by PSA - objectives and main results; PSA approach for the safety assessment of low-power and shutdown states; correlation of initiating events with the PSA level-2 results; safety assessment for fission products tests in the Phebus reactor; use of NPP simulators for applied human factor studies; assessment of the 'deterministic realistic method' applied to large LOCA analysis; assessment of the feasibility of an improvement programme enabling operation of units 3 and 4 of Kozloduy nuclear power plant. Seminar 2 (nuclear installation safety, research): PHEBUS 2K project on severe accidents; current status of the COCOSYS development; fission product modeling in ASTEC; Euratom Framework Programme (FP) research in reactor safety: main achievements of FP- 4 (1994-1998), some preliminary results of FP-5 (1998-2002) and prospects for beyond 2002; development of coupled systems of 3D neutronics and fluid-dynamic system codes and their application for safety

  7. Inspection of Nuclear Power Plant Structures - Overview of Methods and Related Applications

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL

    2009-05-01

    The objectives of this limited study were to provide an overview of the methods that are available for inspection of nuclear power plant reinforced concrete and metallic structures, and to provide an assessment of the status of methods that address inspection of thick, heavily-reinforced concrete and inaccessible areas of the containment metallic pressure boundary. In meeting these objectives a general description of nuclear power plant safety-related structures was provided as well as identification of potential degradation factors, testing and inspection requirements, and operating experience; methods for inspection of nuclear power plant reinforced concrete structures and containment metallic pressure boundaries were identified and described; and applications of nondestructive evaluation methods specifically related to inspection of thick-section reinforced concrete structures and inaccessible portions of containment metallic pressure boundaries were summarized. Recommendations are provided on utilization of test article(s) to further advance nondestructive evaluation methods related to thick-section, heavily-reinforced concrete and inaccessible portions of the metallic pressure boundary representative of nuclear power plant containments. Conduct of a workshop to provide an update on applications and needed developments for nondestructive evaluation of nuclear power plant structures would also be of benefit.

  8. Shamir secret sharing scheme with dynamic access structure (SSSDAS). Case study on nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Thiyagarajan, P.; Thandra, Prasanth Kumar; Rajan, J.; Satyamurthy, S.A.V. [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India). Computer Div.; Aghila, G. [National Institute of Technology, Karaikal (India). Dept. of Computer Science and Engineering

    2015-05-15

    In recent years, due to the sophistication offered by the Internet, strategic organizations like nuclear power plants are linked to the outside world communication through the Internet. The entry of outside world communication into strategic organization (nuclear power plant) increases the hacker's attempts to crack its security and to trace any information which is being sent among the top level officials. Information security system in nuclear power plant is very crucial as even small loophole in the security system will lead to a major disaster. Recent cyber attacks in nuclear power plant provoked information security professionals to look deeply into the information security aspects of strategic organizations (nuclear power plant). In these lines, Shamir secret sharing scheme with dynamic access structure (SSSDAS) is proposed in the paper which provides enhanced security by providing dynamic access structure for each node in different hierarchies. The SSSDAS algorithm can be applied to any strategic organizations with hierarchical structures. In this paper the possible scenarios where SSSDAS algorithm can be applied to nuclear power plant is explained as a case study. The proposed SSSDAS scheme identifies the wrong shares, if any, used for reconstruction of the secret. The SSSDAS scheme also address the three major security parameters namely confidentiality, authentication and integrity.

  9. The challenges of new nuclear projects. E.ON Experience; Los desafios de los nuevos proyectos nucleares. Experiencia de E.ON

    Energy Technology Data Exchange (ETDEWEB)

    Spechty, J.; Perez Rodriguez, J. L.

    2012-07-01

    E.ON is one of the largest privately-owned energy companies in the world. Its portfolio of nuclear assets in composed of 21 nuclear power plants on 13 sites located in Germany and Sweden, 9 of which are directly operated by E.ON. At present E.ON develops large-scale construction projects in two of the European countries willing to commit to new nuclear build-Finland and UK - for which its experience as the best nuclear power plant operator in Europe is key. (Author)

  10. Toward the atomic structure of the nuclear pore complex: when top down meets bottom up.

    Science.gov (United States)

    Hoelz, André; Glavy, Joseph S; Beck, Martin

    2016-07-01

    Elucidating the structure of the nuclear pore complex (NPC) is a prerequisite for understanding the molecular mechanism of nucleocytoplasmic transport. However, owing to its sheer size and flexibility, the NPC is unapproachable by classical structure determination techniques and requires a joint effort of complementary methods. Whereas bottom-up approaches rely on biochemical interaction studies and crystal-structure determination of NPC components, top-down approaches attempt to determine the structure of the intact NPC in situ. Recently, both approaches have converged, thereby bridging the resolution gap from the higher-order scaffold structure to near-atomic resolution and opening the door for structure-guided experimental interrogations of NPC function.

  11. Nuclear moments

    CERN Document Server

    Kopferman, H; Massey, H S W

    1958-01-01

    Nuclear Moments focuses on the processes, methodologies, reactions, and transformations of molecules and atoms, including magnetic resonance and nuclear moments. The book first offers information on nuclear moments in free atoms and molecules, including theoretical foundations of hyperfine structure, isotope shift, spectra of diatomic molecules, and vector model of molecules. The manuscript then takes a look at nuclear moments in liquids and crystals. Discussions focus on nuclear paramagnetic and magnetic resonance and nuclear quadrupole resonance. The text discusses nuclear moments and nucl

  12. Airy structure in $^{16}$O+$^{14}$C nuclear rainbow scattering

    CERN Document Server

    Ohkubo, S

    2015-01-01

    The Airy structure in $^{16}$O+$^{14}$C rainbow scattering is studied with an extended double folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic realistic wave functions for $^{16}$O using a density-dependent nucleon-nucleon force. The experimental angular distributions at $E_L$=132, 281 and 382.2 MeV are well reproduced by the calculations. By studying the energy evolution of the Airy structure, the Airy minimum at around $\\theta$=76$^\\circ$ in the angular distribution at $E_L$=132 MeV is assigned as the second order Airy minimum $A2$ in contrast to the recent literature which assigns it as the third order $A3$. The Airy minima in the 90$^\\circ$ excitation function is investigated in comparison with well-known $^{16}$O+$^{16}$O and $^{12}$C+$^{12}$C systems. Evolution of the Airy structure into the molecular resonances with the $^{16}$O+$^{14}$C cluster structure in the low energy region around $E_{c.m.}$=30 MeV is discussed. It is predicted ...

  13. Numerical simulation of aircraft crash on nuclear containment structure

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, M.A., E-mail: iqbalfce@iitr.ernet.in [Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Rai, S.; Sadique, M.R.; Bhargava, P. [Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer The deformation was more localised at the center of cylindrical portion. Black-Right-Pointing-Pointer The peak deflection at the junction of dome and cylinder was found to be 67 mm. Black-Right-Pointing-Pointer The peak deflection at midpoint of the cylindrical portion was found to be 88.9 mm. Black-Right-Pointing-Pointer The strain rate was found to be an important parameter to effect the deformation. Black-Right-Pointing-Pointer The model without strain rate and 290 s{sup -1} strain rate predicted very high deformations. - Abstract: Numerical simulations were carried with ABAQUS/Explicit finite element code in order to predict the response of BWR Mark III type nuclear containment against Boeing 707-320 aircraft crash. The load of the aircraft was applied using and force history curve. The damaged plasticity model was used to predict the behavior of concrete while the Johnson-Cook elasto-viscoplastic material model was used to incorporate the behavior of steel reinforcement. The crash was considered to occur at two different locations i.e., the midpoint of the cylindrical portion and the junction of dome and cylinder. The midpoint of the cylindrical portion experienced more deformation. The strain rate in the material model was varied and found to have a significant effect on the response of containment. The results of the present investigation were compared with those of the studies available in literature and a close agreement with the previous results was found in terms of maximum target deformation.

  14. Using Grand Challenges For Innovative Teaching in Structural Geology, Geophysics, and Tectonics

    Science.gov (United States)

    McDaris, J. R.; Tewksbury, B. J.; Wysession, M. E.

    2012-12-01

    An innovative approach to teaching involves using the "Big Ideas" or "Grand Challenges" of a field, as determined by the research community in that area, as the basis for classroom activities. There have been several recent efforts in the areas of structural geology, tectonics, and geophysics to determine these Grand Challenges, including the areas of seismology ("Seismological Grand Challenges in Understanding Earth's Dynamic Systems"), mineral physics ("Unlocking the Building Blocks of the Planet"), EarthScope-related science ("Unlocking the Secrets of the North American Continent: An EarthScope Science Plan for 2010-2020"), and structural geology and tectonics (at the Structural Geology and Tectonics Forum held at Williams College in June, 2012). These research community efforts produced frameworks of the essential information for their fields with the aim of guiding future research. An integral part of this, however, is training the next generation of scientists, and using these Big Ideas as the basis for course structures and activities is a powerful way to make this happen. When activities, labs, and homeworks are drawn from relevant and cutting-edge research topics, students can find the material more fascinating and engaging, and can develop a better sense of the dynamic process of scientific discovery. Many creative ideas for incorporating the Grand Challenges of structural geology, tectonics, and geophysics in the classroom were developed at a Cutting Edge workshop on "Teaching Structural Geology, Geophysics, and Tectonics in the 21st Century" held at the University of Tennessee in July, 2012.

  15. Structure Determination of Natural Products by Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Li, Du.

    High-field NMR experiments were used to determine the full structures of six new natural products extracted from plants. These are: four saponins (PT-2, P1, P2 and P3) from the plant Alphitonia zizyphoides found in Samoa; one sesquiterpene (DF-4) from Douglas fir and one diterpene derivative (E-2) from a Chinese medicinal herb. By concerted use of various 1D and 2D NMR techniques, the structures of the above compounds were established and complete resonance assignments were achieved. The 2D INADEQUATE technique coupled with a computerized spectral analysis was extensively used. When carried out on concentrations as low as 60 mg of sample, this technique provided absolute confirmation of the assignments for 35 of the possible 53 C-C bonds for PT-2. On 30 mg of sample of E-21, it revealed 22 of 28 possible C-C bonds.

  16. Bonded repair of composite aircraft structures: A review of scientific challenges and opportunities

    Science.gov (United States)

    Katnam, K. B.; Da Silva, L. F. M.; Young, T. M.

    2013-08-01

    Advanced composite materials have gained popularity in high-performance structural designs such as aerospace applications that require lightweight components with superior mechanical properties in order to perform in demanding service conditions as well as provide energy efficiency. However, one of the major challenges that the aerospace industry faces with advanced composites - because of their inherent complex damage behaviour - is structural repair. Composite materials are primarily damaged by mechanical loads and/or environmental conditions. If material damage is not extensive, structural repair is the only feasible solution as replacing the entire component is not cost-effective in many cases. Bonded composite repairs (e.g. scarf patches) are generally preferred as they provide enhanced stress transfer mechanisms, joint efficiencies and aerodynamic performance. With an increased usage of advanced composites in primary and secondary aerospace structural components, it is thus essential to have robust, reliable and repeatable structural bonded repair procedures to restore damaged composite components. But structural bonded repairs, especially with primary structures, pose several scientific challenges with the current existing repair technologies. In this regard, the area of structural bonded repair of composites is broadly reviewed - starting from damage assessment to automation - to identify current scientific challenges and future opportunities.

  17. Two-Dimensional Nuclear Magnetic Resonance Structure Determination Module for Introductory Biochemistry: Synthesis and Structural Characterization of Lyso-Glycerophospholipids

    Science.gov (United States)

    Garrett, Teresa A.; Rose, Rebecca L.; Bell, Sidney M.

    2013-01-01

    In this laboratory module, introductory biochemistry students are exposed to two-dimensional [superscript 1]H-nuclear magnetic resonance of glycerophospholipids (GPLs). Working in groups of three, students enzymatically synthesized and purified a variety of 2-acyl lyso GPLs. The structure of the 2-acyl lyso GPL was verified using [superscript…

  18. Nuclear Structure Studies of Exotic Nuclei with Radioactive Ion Beams A Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Winger, Jeff Allen [Mississippi State Univ., Mississippi State, MS (United States)

    2016-04-21

    Beta-decay spectroscopy provides important information on nuclear structure and properties needed to understand topics as widely varied as fundamental nuclear astrophysics to applied nuclear reactor design. However, there are significant limitations of our knowledge due to an inability to experimentally measure everything. Therefore, it is often necessary to rely on theoretical calculations which need to be vetted with experimental results. The focus of this report will be results from experimental research performed by the Principal Investigator (PI) and his research group at Mississippi State University in which the group played the lead role in proposing, implementing, performing and analyzing the experiment. This research was carried out at both the National Superconduction Cyclotron Laboratory (NSCL) at Michigan State University and the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. The primary emphasis of the research was the use of \\bdec spectroscopy as a tool to understand the evolution of nuclear structure in neutron-rich nuclei which could then be applied to improve theory and to increase the overall knowledge of nuclear structure.

  19. Nuclear structure corrections to the Lamb shift in $\\mu^3$He$^+$ and $\\mu^3$H

    CERN Document Server

    Dinur, N Nevo; Bacca, S; Barnea, N

    2015-01-01

    Measuring the 2S-2P Lamb shift in a hydrogen-like muonic atom allows one to extract its nuclear charge radius with a high precision that is limited by the uncertainty in the nuclear structure corrections. The charge radius of the proton thus extracted was found to be 7-sigma away from the CODATA value, in what has become the yet unsolved "proton radius puzzle". Further experiments currently aim at the isotopes of hydrogen and helium: the precise extraction of their radii may provide a hint at the solution of the puzzle. We present the first ab initio calculation of nuclear structure corrections, including the nuclear polarization correction, to the 2S-2P transition in $\\mu^3$He$^+$ and $\\mu^3$H, and assess solid theoretical error bars. Our predictions reduce the uncertainty in the nuclear structure corrections to the level of a few percents and will be instrumental to the on-going $\\mu^3$He$^+$ experiment. We also support the mirror $\\mu\\,^3$H system as a candidate for further probing of the nucleon polarizab...

  20. The Legnaro National Laboratories and the SPES facility: nuclear structure and reactions today and tomorrow

    Science.gov (United States)

    de Angelis, Giacomo; Fiorentini, Gianni

    2016-11-01

    There is a very long tradition of studying nuclear structure and reactions at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (Italian Institute of Nuclear Physics). The wide expertise acquired in building and running large germanium arrays has made the laboratories one of the most advanced research centers in γ-ray spectroscopy. The ’gamma group’ has been deeply involved in all the national and international developments of the last 20 years and is currently one of the major contributors to the AGATA project, the first (together with its American counterpart GRETINA) γ-detector array based on γ-ray tracking. This line of research is expected to be strongly boosted by the coming into operation of the SPES radioactive ion beam project, currently under construction at LNL. In this report, written on the occasion of the 40th anniversary of the Nobel prize awarded to Aage Bohr, Ben R Mottelson and Leo Rainwater and particularly focused on the physics of nuclear structure, we intend to summarize the different lines of research that have guided nuclear structure and reaction research at LNL in the last decades. The results achieved have paved the way for the present SPES facility, a new laboratories infrastructure producing and accelerating radioactive ion beams of fission fragments and other isotopes.

  1. Nuclear structure corrections to the Lamb shift in μHe3+ and μ3H

    Science.gov (United States)

    Nevo Dinur, N.; Ji, C.; Bacca, S.; Barnea, N.

    2016-04-01

    Measuring the 2S-2P Lamb shift in a hydrogen-like muonic atom allows one to extract its nuclear charge radius with a high precision that is limited by the uncertainty in the nuclear structure corrections. The charge radius of the proton thus extracted was found to be 7σ away from the CODATA value, in what has become the yet unsolved "proton radius puzzle". Further experiments currently aim at the isotopes of hydrogen and helium: the precise extraction of their radii may provide a hint at the solution of the puzzle. We present the first ab initio calculation of nuclear structure corrections, including the nuclear polarization correction, to the 2S-2P transition in μHe3+ and μ3H, and assess solid theoretical error bars. Our predictions reduce the uncertainty in the nuclear structure corrections to the level of a few percent and will be instrumental to the on-going μHe3+ experiment. We also support the mirror μ3H system as a candidate for further probing of the nucleon polarizabilities and shedding more light on the puzzle.

  2. Nuclear structure far off stability - New results from RISING

    Energy Technology Data Exchange (ETDEWEB)

    Gorska, M [Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64294 Darmstadt (Germany); Grawe, H [Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64294 Darmstadt (Germany); Banu, A [Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64294 Darmstadt (Germany); Buerger, A [Helmholtz-Institut fuer Strahlen- und Kernphysik, Universitaet Bonn (Germany); Doornenbal, P [Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64294 Darmstadt (Germany); Gerl, J [Gesellschaft fuer Schwerionenforschung, Planckstr. 1, 64294 Darmstadt (Germany); Hjorth-Jensen, M [Department of Physics and Center of Mathematics for Applications, University of Oslo, N-0316 Oslo (Norway); Huebel, H [Helmholtz-Institut fuer Strahlen- und Kernphysik, Universitaet Bonn (Germany); Nowacki, F [IReS, F-67037 Strasbourg Cedex 2 (France); Otsuka, T [Department of Physics and Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-Ku, Tokyo 113-0033 (Japan); Reiter, P [Institut fuer Kernphysik, Universitaet zu Cologne (Germany)

    2006-10-10

    A broad range of physics phenomena can be addressed by high-resolution in-beam {gamma}-ray spectroscopy experiments with radioactive beams offered within the Rare ISotopes INvestigation at GSI (RISING) project. It combines the EUROBALL Ge-Cluster detectors, the MINIBALL Ge detectors, the HECTOR-BaF detectors, and the fragment separator FRS. The secondary beams produced at relativistic energies are used for Coulomb excitation or secondary fragmentation experiments to study projectile like nuclei far off the stability line by measuring de-excitation photons. The physics studied comprises the evolution of shell structure towards the drip lines and its signatures as inferred from excitation energies, mirror symmetry and electromagnetic transition strengths. The first results of the 'fast beam campaign' are discussed in comparison to various shell model calculations including the structure of light Sn isotopes based on Coulomb excitation of {sup 108}Sn, the discussion of the N = 32,34 sub-shell closure based on neutron-rich {sup 56,58}Cr isotopes, and the shell structure in light proton-rich Ca isotopes from the fragmentation of a {sup 37}Ca radioactive beam.

  3. Structure, dynamics, evolution, and function of a major scaffold component in the nuclear pore complex.

    Science.gov (United States)

    Sampathkumar, Parthasarathy; Kim, Seung Joong; Upla, Paula; Rice, William J; Phillips, Jeremy; Timney, Benjamin L; Pieper, Ursula; Bonanno, Jeffrey B; Fernandez-Martinez, Javier; Hakhverdyan, Zhanna; Ketaren, Natalia E; Matsui, Tsutomu; Weiss, Thomas M; Stokes, David L; Sauder, J Michael; Burley, Stephen K; Sali, Andrej; Rout, Michael P; Almo, Steven C

    2013-04-02

    The nuclear pore complex, composed of proteins termed nucleoporins (Nups), is responsible for nucleocytoplasmic transport in eukaryotes. Nuclear pore complexes (NPCs) form an annular structure composed of the nuclear ring, cytoplasmic ring, a membrane ring, and two inner rings. Nup192 is a major component of the NPC's inner ring. We report the crystal structure of Saccharomyces cerevisiae Nup192 residues 2-960 [ScNup192(2-960)], which adopts an α-helical fold with three domains (i.e., D1, D2, and D3). Small angle X-ray scattering and electron microscopy (EM) studies reveal that ScNup192(2-960) could undergo long-range transition between "open" and "closed" conformations. We obtained a structural model of full-length ScNup192 based on EM, the structure of ScNup192(2-960), and homology modeling. Evolutionary analyses using the ScNup192(2-960) structure suggest that NPCs and vesicle-coating complexes are descended from a common membrane-coating ancestral complex. We show that suppression of Nup192 expression leads to compromised nuclear transport and hypothesize a role for Nup192 in modulating the permeability of the NPC central channel.

  4. Technology development on the assessment of structural integrity of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jeong Moon; Choun, Y. S.; Choi, I. K. and others

    1999-04-01

    Nuclear power plants in Korea show drop off in their performance and safety margin as the age of plants increase. The reevaluation of Kori-1 Unit on its performance and safety for life extension is expected in the near future. However, technologies and information related are insufficient to quantitatively estimate them. The final goal of this study is to develop the basic testing and evaluation techniques related with structural integrity of important nuclear equipment and structures. A part of the study includes development of equipment qualification technique. To ensure the structural integrity of structures, systems, and equipment in nuclear power plants, the following 5 research tasks were performed in the first year. - Analysis of dynamic characteristics of reactor internals - Analysis of engineering characteristics of instrumental earthquakes recorded in Korea - Analysis of ultimate pressure capacity and failure mode of containments building - Development of advanced NDE techniques using ultrasonic resonance scattering - Development of equipment qualification technique against vibration aging. These technologies developed in this study can be used to ensure the structural safety of operational nuclear power plants, and for the long-term life management. (author)

  5. Time-domain soil-structure interaction analysis of nuclear facilities

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Justin L., E-mail: justin.coleman@inl.gov [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83402 (United States); Bolisetti, Chandrakanth, E-mail: chandrakanth.bolisetti@inl.gov [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83402 (United States); Whittaker, Andrew S., E-mail: awhittak@buffalo.edu [University at Buffalo, The State University of New York, North Campus, 212 Ketter Hall, Amherst, NY 14260 (United States)

    2016-03-15

    The Nuclear Regulatory Commission (NRC) regulation 10 CFR Part 50 Appendix S requires consideration of soil-structure interaction (SSI) in nuclear power plant (NPP) analysis and design. Soil-structure interaction analysis for NPPs is routinely carried out using guidance provided in the ASCE Standard 4-98 titled “Seismic Analysis of Safety-Related Nuclear Structures and Commentary”. This Standard, which is currently under revision, provides guidance on linear seismic soil-structure-interaction (SSI) analysis of nuclear facilities using deterministic and probabilistic methods. A new appendix has been added to the forthcoming edition of ASCE Standard 4 to provide guidance for time-domain, nonlinear SSI (NLSSI) analysis. Nonlinear SSI analysis will be needed to simulate material nonlinearity in soil and/or structure, static and dynamic soil pressure effects on deeply embedded structures, local soil failure at the foundation-soil interface, nonlinear coupling of soil and pore fluid, uplift or sliding of the foundation, nonlinear effects of gaps between the surrounding soil and the embedded structure and seismic isolation systems, none of which can be addressed explicitly at present. Appendix B of ASCE Standard 4 provides general guidance for NLSSI analysis but will not provide a methodology for performing the analysis. This paper provides a description of an NLSSI methodology developed for application to nuclear facilities, including NPPs. This methodology is described as series of sequential steps to produce reasonable results using any time-domain numerical code. These steps require some numerical capabilities, such as nonlinear soil constitutive models, which are also described in the paper.

  6. The polariser beamline at TRIUMF for nuclear structure physics

    Science.gov (United States)

    Voss, A.; Pearson, M. R.; Levy, C. D. P.; Billowes, J.; Buchinger, F.; Chow, K. H.; Crawford, J. E.; Hossein, M. D.; Kiefl, R. F.; Macfarlane, W. A.; Mané, E.; Morris, G. D.; Parolin, T. J.; Saadaoui, H.; Salman, Z.; Shelbaya, O. T. J.; Smadella, M.; Song, Q.; Wang, D.

    2011-10-01

    Originally built to provide polarised ion beams for condensed matter experiments, the polariser beamline at TRIUMF is coupled to both beta-NMR and beta-NQR spectrometers. In addition, the beam can be passed through a radio-frequency quadrupole cooler and buncher (RFQ) providing bunched beams. Recently, a laser spectroscopy and beta-NQR program was started to investigate the ground state structure of exotic nuclei. Results from recent experiments including zero-field beta-NQR studies to determine the quadrupole moment of the halo nucleus Li-11 and laser spectroscopy to determine the charge radius of Rb-74.

  7. The Shell Model as Unified View of Nuclear Structure

    CERN Document Server

    Caurier, E; Nowacki, F; Poves, A; Zuker, A P

    2004-01-01

    The last decade has witnessed both quantitative and qualitative progresses in Shell Model studies, which have resulted in remarkable gains in our understanding of the structure of the nucleus. Indeed, it is now possible to diagonalize matrices in determinantal spaces of dimensionality up to 10^9 using the Lanczos tridiagonal construction, whose formal and numerical aspects we will analyze. Besides, many new approximation methods have been developed in order to overcome the dimensionality limitations. Furthermore, new effective nucleon-nucleon interactions have been constructed that contain both two and three-body contributions. The former are derived from realistic potentials (i.e., consistent with two nucleon data). The latter incorporate the pure monopole terms necessary to correct the bad saturation and shell-formation properties of the realistic two-body forces. This combination appears to solve a number of hitherto puzzling problems. In the present review we will concentrate on those results which illust...

  8. Advanced density matrix renormalization group method for nuclear structure calculations

    CERN Document Server

    Legeza, Ö; Poves, A; Dukelsky, J

    2015-01-01

    We present an efficient implementation of the Density Matrix Renormalization Group (DMRG) algorithm that includes an optimal ordering of the proton and neutron orbitals and an efficient expansion of the active space utilizing various concepts of quantum information theory. We first show how this new DMRG methodology could solve a previous $400$ KeV discrepancy in the ground state energy of $^{56}$Ni. We then report the first DMRG results in the $pf+g9/2$ shell model space for the ground $0^+$ and first $2^+$ states of $^{64}$Ge which are benchmarked with reference data obtained from Monte Carlo shell model. The corresponding correlation structure among the proton and neutron orbitals is determined in terms of the two-orbital mutual information. Based on such correlation graphs we propose several further algorithmic improvement possibilities that can be utilized in a new generation of tensor network based algorithms.

  9. Advanced density matrix renormalization group method for nuclear structure calculations

    Science.gov (United States)

    Legeza, Ã.-.; Veis, L.; Poves, A.; Dukelsky, J.

    2015-11-01

    We present an efficient implementation of the Density Matrix Renormalization Group (DMRG) algorithm that includes an optimal ordering of the proton and neutron orbitals and an efficient expansion of the active space utilizing various concepts of quantum information theory. We first show how this new DMRG methodology could solve a previous 400 keV discrepancy in the ground state energy of 56Ni. We then report the first DMRG results in the p f +g 9 /2 shell model space for the ground 0+ and first 2+ states of 64Ge which are benchmarked with reference data obtained from a Monte Carlo shell model. The corresponding correlation structure among the proton and neutron orbitals is determined in terms of two-orbital mutual information. Based on such correlation graphs we propose several further algorithmic improvement possibilities that can be utilized in a new generation of tensor network based algorithms.

  10. Developing a Computerized Aging Management System for Concrete Structures in Finnish Nuclear Power Plants

    Directory of Open Access Journals (Sweden)

    Hradil P.

    2013-07-01

    Full Text Available Finland has four nuclear reactors units in two power plants. The first unit started operation in 1977 and in the early 1980's all four units were in use. During the last few years the aging management of the Nuclear Power Plant's (NPP concrete structures has grown an important issue because the existing structures are reaching the end of their licensed operating lifetime (about 40 years. Therefore the nuclear power companies are developing aging management systems to avoid premature degradation of NPP facilities and to be able to extend their operating lifetime. This paper is about the development of a computerized ageing management system for the nuclear power plants concrete structures. The computerized ageing management system is built upon central database and implementation applications. It will assist the personnel of power companies to implement the aging management activities at different phases of the lifetime of a power plant. It will provide systematic methods for planning, surveillance, inspection, monitoring, condition assessment, maintenance and repair of structures.

  11. Developing a Computerized Aging Management System for Concrete Structures in Finnish Nuclear Power Plants

    Science.gov (United States)

    Al-Neshawy, F.; Piironen, J.; Sistonen, E.; Vesikari, E.; Tuomisto, M.; Hradil, P.; Ferreira, M.

    2013-07-01

    Finland has four nuclear reactors units in two power plants. The first unit started operation in 1977 and in the early 1980's all four units were in use. During the last few years the aging management of the Nuclear Power Plant's (NPP) concrete structures has grown an important issue because the existing structures are reaching the end of their licensed operating lifetime (about 40 years). Therefore the nuclear power companies are developing aging management systems to avoid premature degradation of NPP facilities and to be able to extend their operating lifetime. This paper is about the development of a computerized ageing management system for the nuclear power plants concrete structures. The computerized ageing management system is built upon central database and implementation applications. It will assist the personnel of power companies to implement the aging management activities at different phases of the lifetime of a power plant. It will provide systematic methods for planning, surveillance, inspection, monitoring, condition assessment, maintenance and repair of structures.

  12. Neutron Halo and Nuclear Shell Structure in New Nuclide 31Ne

    Institute of Scientific and Technical Information of China (English)

    REN ZhongZhou; CHEN BaoQiu; MA ZhongYu; XU GongOu

    2001-01-01

    The ground state properties of new nuclide 31Ne are investigated within the framework of the densitydependent relativistic mean-field theory. One-neutron halo in 31Ne is predicted. Calculations also show that the ground state of31Ne is (3/2)- and it can be used for the testing of the nuclear shell structure near the neutron-drip line.``

  13. The determination of the in situ structure by nuclear spin contrast variation

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS Forschungszentrum, Geesthacht (Germany); Nierhaus, K.H. [Max-Planch-Institut fuer Molekulare Genetik, Berlin (Germany)

    1994-12-31

    Polarized neutron scattering from polarized nuclear spins in hydrogenous substances opens a new way of contrast variation. The enhanced contrast due to proton spin polarization was used for the in situ structure determination of tRNA of the functional complex of the E.coli ribosome.

  14. An enhancement of NASTRAN for the seismic analysis of structures. [nuclear power plants

    Science.gov (United States)

    Burroughs, J. W.

    1980-01-01

    New modules, bulk data cards and DMAP sequence were added to NASTRAN to aid in the seismic analysis of nuclear power plant structures. These allow input consisting of acceleration time histories and result in the generation of acceleration floor response spectra. The resulting system contains numerous user convenience features, as well as being reasonably efficient.

  15. Nuclear security towards the adequate answers to the new challenge of nuclear and radiological terrorism; Seguridad nuclear hacia las respuestas adecuadas al nuevo reto del terrorismo nuclear y radiologico

    Energy Technology Data Exchange (ETDEWEB)

    Puig, D.E. [Pza. Cagancha 1387 / 404, Montevideo (Uruguay)]. e-mail: d.puig@adinet.com.uy

    2006-07-01

    The globalization phenomenon and the process of regional integration have generated new and defiant characteristics in the criminal activation, the one that has acquired growing trans national dimension. After September 11, 2001 it should to have bigger international initiative to reinforce the safety of materials and facilities in the entire world and to apply the international recommendations for to assure that all the nuclear materials of not used bombs are registered and secure of sabotage. Thousands of radioactive sources exist in the world. Possibility that the terrorists use radioactive sources as attack instruments since its are more easily available and its are more easy too to obtain in comparison with the uranium or plutonium classified for weapons. Dirty bomb. Effects of the Radiations. The Goiania accident. 'Orphans' sources Illicit traffic of radioactive material. Security. Measures of Physical Protection. Security of the radioactive sources. Role of the IAEA and other international organisms and regional CAN-MERCOSUR. Nuclear security and Legal frame. International and national instruments against the nuclear and radiological terrorism. Study from a proposal to Pan-American level to make in front of the problem. (Author)

  16. Structural determinants of nuclear export signal orientation in binding to exportin CRM1.

    Science.gov (United States)

    Fung, Ho Yee Joyce; Fu, Szu-Chin; Brautigam, Chad A; Chook, Yuh Min

    2015-09-08

    The Chromosome Region of Maintenance 1 (CRM1) protein mediates nuclear export of hundreds of proteins through recognition of their nuclear export signals (NESs), which are highly variable in sequence and structure. The plasticity of the CRM1-NES interaction is not well understood, as there are many NES sequences that seem incompatible with structures of the NES-bound CRM1 groove. Crystal structures of CRM1 bound to two different NESs with unusual sequences showed the NES peptides binding the CRM1 groove in the opposite orientation (minus) to that of previously studied NESs (plus). Comparison of minus and plus NESs identified structural and sequence determinants for NES orientation. The binding of NESs to CRM1 in both orientations results in a large expansion in NES consensus patterns and therefore a corresponding expansion of potential NESs in the proteome.

  17. The Diamond Light Source and the challenges ahead for structural biology: some informal remarks.

    Science.gov (United States)

    Ramakrishnan, V

    2015-03-06

    The remarkable advances in structural biology in the past three decades have led to the determination of increasingly complex structures that lie at the heart of many important biological processes. Many of these advances have been made possible by the use of X-ray crystallography using synchrotron radiation. In this short article, some of the challenges and prospects that lie ahead will be summarized.

  18. On the unification of nuclear-structure theory: A response to Bortignon and Broglia

    Science.gov (United States)

    Cook, Norman D.

    2016-09-01

    Nuclear-structure theory is unusual among the diverse fields of quantum physics. Although it provides a coherent description of all known isotopes on the basis of a quantum-mechanical understanding of nucleon states, nevertheless, in the absence of a fundamental theory of the nuclear force acting between nucleons, the prediction of all ground-state and excited-state nuclear binding energies is inherently semi-empirical. I suggest that progress can be made by returning to the foundational work of Eugene Wigner from 1937, where the mathematical symmetries of nucleon states were first defined. Those symmetries were later successfully exploited in the development of the independent-particle model ( IPM ˜ shell model , but the geometrical implications noted by Wigner were neglected. Here I review how the quantum-mechanical, but remarkably easy-to-understand geometrical interpretation of the IPM provides constraints on the parametrization of the nuclear force. The proposed "geometrical IPM" indicates a way forward toward the unification of nuclear-structure theory that Bortignon and Broglia have called for.

  19. Study of the nuclear structure of {sup 155}Eu; Estudo da estrutura nuclear do {sup 155}Eu

    Energy Technology Data Exchange (ETDEWEB)

    Genezini, Frederico Antonio

    2004-07-01

    The {sup 155}Eu nuclide was investigated by the directional angular correlation technique following the {beta} decay of {sup 155}Sm. The angular correlation measurements were carried out using a setup with 4 Ge detectors and a multi parametric data acquisition system. To perform the data analysis a new methodology was developed . The multipole mixing ratios of twenty sixty {gamma}- transitions were determined. Seven of them agreed with the results of earlier angular correlation studies and nineteen obtained for the first time confirmed the multipolarity suggested in earlier electron capture studies. Besides, the spin of the level at 1106.83 keV as well as the parity of the level at 1301.41 keV have also been suggested. The nuclear structure of {sup 155}Eu was discussed successfully in terms of the single particle model using a deformed Woods-Saxon potential plus residual pairing interaction permitting the description of the rotational quasi-proton band heads. (author)

  20. Theoretical Borderlands: Using Multiple Theoretical Perspectives to Challenge Inequitable Power Structures in Student Development Theory

    Science.gov (United States)

    Abes, Elisa S.

    2009-01-01

    This article is an exploration of possibilities and methodological considerations for using multiple theoretical perspectives in research that challenges inequitable power structures in student development theory. Specifically, I explore methodological considerations when partnering queer theory and constructivism in research on lesbian identity…

  1. Large-Scale Computations Leading to a First-Principles Approach to Nuclear Structure

    Energy Technology Data Exchange (ETDEWEB)

    Ormand, W E; Navratil, P

    2003-08-18

    We report on large-scale applications of the ab initio, no-core shell model with the primary goal of achieving an accurate description of nuclear structure from the fundamental inter-nucleon interactions. In particular, we show that realistic two-nucleon interactions are inadequate to describe the low-lying structure of {sup 10}B, and that realistic three-nucleon interactions are essential.

  2. Chaotic features of nuclear structure and dynamics: selected topics

    Science.gov (United States)

    Zelevinsky, Vladimir; Volya, Alexander

    2016-03-01

    Quantum chaos has become an important element of our knowledge about physics of complex systems. In typical mesoscopic systems of interacting particles the dynamics invariably become chaotic when the level density, growing by combinatorial reasons, leads to the increasing probability of mixing simple mean-field (particle-hole) configurations. The resulting stationary states have exceedingly complicated structures that are comparable to those in random matrix theory. We discuss the main properties of mesoscopic quantum chaos and show that it can serve as a justification for application of statistical mechanics to mesoscopic systems. We show that quantum chaos becomes a powerful instrument for experimental, theoretical and computational work. The generalization to open systems and effects in the continuum are discussed with the help of the effective non-Hermitian Hamiltonian; it is shown how to formulate this approach for numerous problems of quantum signal transmission. The artificially introduced randomness can also be helpful for a deeper understanding of physics. We indicate the problems that require more investigation so as to be understood further.

  3. Nuclear power plant life extension: How aging affects performance of containments & other structures

    Institute of Scientific and Technical Information of China (English)

    Robert A Dameron; Sun Junling

    2013-01-01

    This paper focuses on how aging can affect performance of safety-related structures in nuclear power plant (NPP).Knowledge and assessment of impacts of aging on structures are essential to plant life extension analysis,especially performance to severe loadings such as loss-of-coolant-accidents or major seismic events.Plant life extension issues are of keen interest in countries (like the United States) which have a large,aging fleet of NPPs.This paper addresses the overlap and relationship of structure aging to severe loading performance,with particular emphasis on containment structures.

  4. Accessing nuclear structure for field emission, in lens, scanning electron microscopy (FEISEM).

    Science.gov (United States)

    Allen, T D; Bennion, G R; Rutherford, S A; Reipert, S; Ramalho, A; Kiseleva, E; Goldberg, M W

    1996-01-01

    Scanning electron microscopy (SEM) has had a shorter time course in biology than conventional transmission electron microscopy (TEM) but has nevertheless produced a wealth of images that have significantly complemented our perception of biological structure and function from TEM information. By its nature, SEM is a surface imaging technology, and its impact at the subcellular level has been restricted by the considerably reduced resolution in conventional SEM in comparison to TEM. This restriction has been removed by the recent advent of high-brightness sources used in lensfield emission instruments (FEISEM) which have produced resolution of around 1 nanometre, which is not usually a limiting figure for biological material. This communication reviews our findings in the use of FEISEM in the imaging of nuclear surfaces, then associated structures, such as nuclear pore complexes, and the relationships of these structures with cytoplasmic and nucleoplasmic elements. High resolution SEM allows the structurally orientated cell biologist to visualise, directly and in three dimensions, subcellular structure and its modulation with a view to understanding, its functional significance. Clearly, intracellular surfaces require separation from surrounding structural elements in vivo to allow surface imaging, and we review a combination of biochemical and mechanical isolation methods for nuclear surfaces.

  5. Structural and dynamic properties of amorphous solid dispersions: the role of solid-state nuclear magnetic resonance spectroscopy and relaxometry.

    Science.gov (United States)

    Paudel, Amrit; Geppi, Marco; Van den Mooter, Guy

    2014-09-01

    Amorphous solid dispersions (ASDs) are one of the frontier strategies to improve solubility and dissolution rate of poorly soluble drugs and hence tackling the growing challenges in oral bioavailability. Pharmaceutical performance, physicochemical stability, and downstream processability of ASD largely rely on the physical structure of the product. This necessitates in-depth characterization of ASD microstructure. Solid-state nuclear magnetic resonance (SS-NMR) techniques bear the ultimate analytical capabilities to provide the molecular level information on the dynamics and phase compositions of amorphous dispersions. SS-NMR spectroscopy/relaxometry, as a single and nondestructive technique, can reveal diverse and critical structural information of complex ASD formulations that are barely amenable from any other existing technique. The purpose of the current article is to review the recent most important studies on various sophisticated and information-rich one-dimensional and two-dimensional SS-NMR spectroscopy/relaxometry for the analysis of molecular mobility, miscibility, drug-carrier interactions, crystallinity, and crystallization in ASD. Some specific examples on microstructural elucidations of challenging ASD using multidimensional and multinuclear SS-NMR are presented. Additionally, some relevant examples on the utility of solution-NMR and NMR-imaging techniques for the investigation of the dissolution behavior of ASD are gathered.

  6. Nuclear structure in strong magnetic fields: nuclei in the crust of a magnetar

    CERN Document Server

    Arteaga, Daniel Pena; Khan, Elias; Ring, Peter

    2011-01-01

    Covariant density functional theory is used to study the effect of strong magnetic fields, up to the limit predicted for neutron stars (for magnetars $B \\approx10^{18}$G), on nuclear structure. All new terms in the equation of motion resulting from time reversal symmetry breaking by the magnetic field and the induced currents, as well as axial deformation, are taken into account in a self-consistent fashion. For nuclei in the iron region of the nuclear chart it is found that fields in the order of magnitude of $10^{17}$G significantly affect bulk properties like masses and radii.

  7. Quality assessment of layer-structured semiconductor single crystals by nuclear quadruple resonance method

    Science.gov (United States)

    Samila, Andriy; Khandozhko, Alexander; Lastivka, Galina; Politansky, Leonid; Khandozhko, Victor

    2015-11-01

    A method for quality assessment of layer-structured semiconductor single crystals (InSe, GaSe, GaS) grown in evacuated ampoules by the Bridgman technique is proposed. For this purpose, nuclear quadruple resonance method with a consecutive scanning of the entire sample volume and evaluation of crystal perfection by the resulting spectra is used. Effective interaction between high-frequency field and crystal and, accordingly, restriction of scanning area of sample under study is provided with the use of a two-way saddle-shaped coil for a nuclear quadruple resonance spectrometer.

  8. A Neutron Diffraction Study of the Nuclear and Magnetic Structure of MnNb2O6

    DEFF Research Database (Denmark)

    Nielsen, Oliver Vindex; Lebech, Bente; Krebs Larsen, F.;

    1976-01-01

    A neutron diffraction study was made of the nuclear and the magnetic structure of MnNb2O6 single crystals. The thirteen nuclear parameters (space group Pbcn) were determined from 304 reflections at room temperature. The antiferromagnetic structure (Neel temperature=4.4K), determined at 1.2K, is a...

  9. Excitations in superfluid systems: contributions of the nuclear structure; Excitations dans les systemes superfluides: contributions de la structure nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Khan, E

    2005-12-15

    The author presents successively the theoretical aspect, the experimental aspect and the applied aspect of excitations in nuclear structures. The quasi-particle random phase approximation (QRPA) tool is first described. Recent approaches on QRPA are based on the theory of the density function where the ground state and excited states are described from the same nucleon-nucleon interaction. 2 methods for measuring the collective excitations are then presented: the proton scattering that has the potentiality to investigate the evolution of magicity, the second method is in fact a new method for measuring the giant mono-polar resonance (GMP) in exotic nuclei. Nuclear reactions are considered as a compulsory step on the way from observables like cross-sections to nuclear structure. The author highlights the assets of the convolution model that can generate the optical potential from the effective nucleon-nucleon interaction and from proton and neutron densities of the nuclei involved. R-processes in nucleosynthesis and neutron stars are reviewed as applications of collective excitations in the field of nuclear astrophysics. (A.C.)

  10. NVR-BIP: Nuclear Vector Replacement using Binary Integer Programming for NMR Structure-Based Assignments.

    Science.gov (United States)

    Apaydin, Mehmet Serkan; Çatay, Bülent; Patrick, Nicholas; Donald, Bruce R

    2011-05-01

    Nuclear magnetic resonance (NMR) spectroscopy is an important experimental technique that allows one to study protein structure and dynamics in solution. An important bottleneck in NMR protein structure determination is the assignment of NMR peaks to the corresponding nuclei. Structure-based assignment (SBA) aims to solve this problem with the help of a template protein which is homologous to the target and has applications in the study of structure-activity relationship, protein-protein and protein-ligand interactions. We formulate SBA as a linear assignment problem with additional nuclear overhauser effect constraints, which can be solved within nuclear vector replacement's (NVR) framework (Langmead, C., Yan, A., Lilien, R., Wang, L. and Donald, B. (2003) A Polynomial-Time Nuclear Vector Replacement Algorithm for Automated NMR Resonance Assignments. Proc. the 7th Annual Int. Conf. Research in Computational Molecular Biology (RECOMB), Berlin, Germany, April 10-13, pp. 176-187. ACM Press, New York, NY. J. Comp. Bio., (2004), 11, pp. 277-298; Langmead, C. and Donald, B. (2004) An expectation/maximization nuclear vector replacement algorithm for automated NMR resonance assignments. J. Biomol. NMR, 29, 111-138). Our approach uses NVR's scoring function and data types and also gives the option of using CH and NH residual dipolar coupling (RDCs), instead of NH RDCs which NVR requires. We test our technique on NVR's data set as well as on four new proteins. Our results are comparable to NVR's assignment accuracy on NVR's test set, but higher on novel proteins. Our approach allows partial assignments. It is also complete and can return the optimum as well as near-optimum assignments. Furthermore, it allows us to analyze the information content of each data type and is easily extendable to accept new forms of input data, such as additional RDCs.

  11. Structural mechanism of nuclear transport mediated by importin β and flexible amphiphilic proteins.

    Science.gov (United States)

    Yoshimura, Shige H; Kumeta, Masahiro; Takeyasu, Kunio

    2014-12-02

    Karyopherin β family proteins mediate the nuclear/cytoplasmic transport of various proteins through the nuclear pore complex (NPC), although they are substantially larger than the size limit of the NPC.To elucidate the molecular mechanism underlying this paradoxical function, we focused on the unique structures called HEAT repeats, which consist of repetitive amphiphilic α helices. An in vitro transport assay and FRAP analyses demonstrated that not only karyopherin β family proteins but also other proteins with HEAT repeats could pass through the NPC by themselves, and serve as transport mediators for their binding partners. Biochemical and spectroscopic analyses and molecular dynamics simulations of purified HEAT-rich proteins revealed that they interact with hydrophobic groups, including phenyl and alkyl groups, and undergo reversible conformational changes in tertiary structures, but not in secondary structures. These results show that conformational changes in the flexible amphiphilic motifs play a critical role in translocation through the NPC.

  12. Aging population in change – a crucial challenge for structurally weak rural areas in Austria

    Directory of Open Access Journals (Sweden)

    Fischer Tatjana

    2014-03-01

    Full Text Available Besides population decline, structurally weak rural areas in Austria face a new challenge related to demographic change: the increasing heterogeneity of their aging population. From the example of the so-called ‘best agers’ - comprising people aged 55 to 65 years - this contribution makes visible patterns and consequences of growing individualized spatial behaviour and spatial perception. Furthermore, contradictions between claims, wishes and expectations and actual engagement and commitment to their residential rural municipalities are being pointed out. These empirically-based facts are rounded off by considerations on the best agers’ future migration-behaviour and the challenges for spatial planning at the municipal level.

  13. The long and winding road from chiral effective Lagrangians to nuclear structure

    CERN Document Server

    Meißner, Ulf-G

    2015-01-01

    I review the chiral dynamics of nuclear physics. In the first part, I discuss the new developments in the construction of the forces between two, three and four nucleons which have been partly carried out to fifth order in the chiral expansion. It is also shown that based on these forces in conjunction with the estimation of the corresponding theoretical uncertainties, the need for three-nucleon forces in few nucleon systems can be unambiguously established. I also introduce the lattice formulation of these forces, which allow for truly ab initio calculations of nuclear structure and reactions. I present some pertinent results of the nuclear lattice approach. Finally, I discuss how few-nucleon systems and nuclei can be used to explore symmetries and physics within and beyond the Standard Model.

  14. Seismic resistance design of nuclear power plant building structures in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Kitano, Takehito [Kansai Electric Power Co., Inc., Osaka (Japan)

    1997-03-01

    Japan is one of the countries where earthquakes occur most frequently in the world and has incurred a lot of disasters in the past. Therefore, the seismic resistance design of a nuclear power plant plays a very important role in Japan. This report describes the general method of seismic resistance design of a nuclear power plant giving examples of PWR and BWR type reactor buildings in Japan. Nuclear facilities are classified into three seismic classes and is designed according to the corresponding seismic class in Japan. Concerning reactor buildings, the short-term allowable stress design is applied for the S1 seismic load and it is confirmed that the structures have a safety margin against the S2 seismic load. (J.P.N.)

  15. France, Germany and the nuclear challenge; La France, l'Allemagne et l'enjeu nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Turkish, F

    2004-11-15

    Taking into account the french and german relations concerning the nuclear activities, the nuclear phaseout decided by the german government in 1998 presents inevitable impacts in France. The author discusses the constraints bound to this project (industrial interests, energy dependence...), the short dated phaseout project and the consequences for the relations of the two countries, Germany and France. (A.L.B.)

  16. Telomere dysfunction and chromosome structure modulate the contribution of individual chromosomes in abnormal nuclear morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Pampalona, J.; Soler, D.; Genesca, A. [Department of Cell Biology, Physiology and Immunology, Universitat Autonoma de Barcelona, Bellaterra E-08193 (Spain); Tusell, L., E-mail: laura.tusell@uab.es [Department of Cell Biology, Physiology and Immunology, Universitat Autonoma de Barcelona, Bellaterra E-08193 (Spain)

    2010-01-05

    The cytokinesis-block micronucleus assay has emerged as a biomarker of chromosome damage relevant to cancer. Although it was initially developed to measure micronuclei, it is also useful for measuring nucleoplasmic bridges and nuclear buds. Abnormal nuclear morphologies are frequently observed in malignant tissues and short-term tumour cell cultures. Changes in chromosome structure and number resulting from chromosome instability are important factors in oncogenesis. Telomeres have become key players in the initiation of chromosome instability related to carcinogenesis by means of breakage-fusion-bridge cycles. To better understand the connection between telomere dysfunction and the appearance of abnormal nuclear morphologies, we have characterised the presence of micronuclei, nucleoplasmic bridges and nuclear buds in human mammary primary epithelial cells. These cells can proliferate beyond the Hayflick limit by spontaneously losing expression of the p16{sup INK4a} protein. Progressive telomere shortening leads to the loss of the capping function, and the appearance of end-to-end chromosome fusions that can enter into breakage-fusion-bridge cycles generating massive chromosomal instability. In human mammary epithelial cells, different types of abnormal nuclear morphologies were observed, however only nucleoplasmatic bridges and buds increased significantly with population doublings. Fluorescent in situ hybridisation using centromeric and painting specific probes for chromosomes with eroded telomeres has revealed that these chromosomes are preferentially included in the different types of abnormal nuclear morphologies observed, thus reflecting their common origin. Accordingly, real-time imaging of cell divisions enabled us to determine that anaphase bridge resolution was mainly through chromatin breakage and the formation of symmetric buds in daughter nuclei. Few micronuclei emerged in this cell system thus validating the scoring of nucleoplasmic bridges and

  17. Laymen's demand on an understandable safety analysis for a nuclear waste repository. A communication challenge

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, T.L.; Thunberg, A.M. [KASAM - Swedish National Council for Nuclear Waste (Sweden)

    1999-12-01

    This paper is a summary in English of some impressions from a seminar 'Safety Analysis of the Final Disposal of Nuclear Waste. An issue for specialists only or for all of us?' The seminar was held in Swedish and was arranged by KASAM in Nykoeping, Sweden in November 1997. A report in Swedish from the seminar has been published. The seminar was arranged in response to a request from representatives from some of the municipalities concerned by the feasibility studies, which are part of the siting process. They had noticed that it is very hard for people without specialist competence to get an understanding of the safety issues based on the available information. There is a need for a presentation of the safety analysis, which is adopted not only for the need of the safety authorities, which have their own expertise, but also for the need of laymen who are involved in issues about the design, siting and safety of a final repository. Therefore, the seminar was mainly intended for representatives for the citizens (i.e. politicians) from the municipalities involved in the ongoing feasibility studies in Sweden. Some representatives from different environmental organisations opposing final disposal were also invited as well as representatives from the nuclear industry and from the concerned Swedish authorities. The seminar was structured in four sessions The handling of risk in the modern society - risk assessment and risk comparisons; The safety analysis and its role for the citizens; What can actually happen - in our own time and in the future?; Group discussions. In order to give a realistic picture of the intense debate, which at least in some of the municipalities had been very apparent, the organisers had chosen to make SKB and Greenpeace main actors at the seminar, such as they appeared in connection with campaign before the referendum at Malaa. Parts of the seminar were arranged like a hearing, led by a science journalist. The intention with this paper is

  18. Quantum Trajectory-Electronic Structure Approach for Exploring Nuclear Effects in the Dynamics of Nanomaterials.

    Science.gov (United States)

    Garashchuk, Sophya; Jakowski, Jacek; Wang, Lei; Sumpter, Bobby G

    2013-12-10

    A massively parallel, direct quantum molecular dynamics method is described. The method combines a quantum trajectory (QT) representation of the nuclear wave function discretized into an ensemble of trajectories with an electronic structure (ES) description of electrons, namely using the density functional tight binding (DFTB) theory. Quantum nuclear effects are included into the dynamics of the nuclei via quantum corrections to the classical forces. To reduce computational cost and increase numerical accuracy, the quantum corrections to dynamics resulting from localization of the nuclear wave function are computed approximately and included into selected degrees of freedom representing light particles where the quantum effects are expected to be the most pronounced. A massively parallel implementation, based on the message passing interface allows for efficient simulations of ensembles of thousands of trajectories at once. The QTES-DFTB dynamics approach is employed to study the role of quantum nuclear effects on the interaction of hydrogen with a model graphene sheet, revealing that neglect of nuclear effects can lead to an overestimation of adsorption.

  19. 3rd International Conference on High-energy Physics and Nuclear Structure

    CERN Document Server

    High energy physics and nuclear structure

    1970-01-01

    In preparing the program for this Conference, the third in the series, it soon became evident that it was not possible to in­ clude in a conference of reasonable duration all the topics that might be subsumed under the broad title, "High Energy Physics and Nuclear Structure. " From their initiation, in 1963, it has been as much the aim of these Conferences to provide some bridges between the steadily separating domains of particle and nuclear physics, as to explore thoroughly the borderline territory between the two -­ the sort of no-man's-land that lies unclaimed, or claimed by both sides. The past few years have witnessed the rapid development of many new routes connecting the two major areas of 'elementary par­ ticles' and 'nuclear structure', and these now spread over a great expanse of physics, logically perhaps including the whole of both subjects. (As recently as 1954, an International Conference on 'Nuclear and Meson Physics' did, in fact, embrace both fields!) Since it is not now possibl...

  20. In silico analyses of dystrophin Dp40 cellular distribution, nuclear export signals and structure modeling

    Directory of Open Access Journals (Sweden)

    Alejandro Martínez-Herrera

    2015-09-01

    Full Text Available Dystrophin Dp40 is the shortest protein encoded by the DMD (Duchenne muscular dystrophy gene. This protein is unique since it lacks the C-terminal end of dystrophins. In this data article, we describe the subcellular localization, nuclear export signals and the three-dimensional structure modeling of putative Dp40 proteins using bioinformatics tools. The Dp40 wild type protein was predicted as a cytoplasmic protein while the Dp40n4 was predicted to be nuclear. Changes L93P and L170P are involved in the nuclear localization of Dp40n4 protein. A close analysis of Dp40 protein scored that amino acids 93LEQEHNNLV101 and 168LLLHDSIQI176 could function as NES sequences and the scores are lost in Dp40n4. In addition, the changes L93/170P modify the tertiary structure of putative Dp40 mutants. The analysis showed that changes of residues 93 and 170 from leucine to proline allow the nuclear localization of Dp40 proteins. The data described here are related to the research article entitled “EF-hand domains are involved in the differential cellular distribution of dystrophin Dp40” (J. Aragón et al. Neurosci. Lett. 600 (2015 115–120 [1].

  1. Nuclear structure and the fate of core collapse (Type II) supernova

    Energy Technology Data Exchange (ETDEWEB)

    Gai, Moshe [LNS at Avery Point, University of Connecticut, Groton, CT 06340-6097 (United States); Wright Lab, Dept. of Physics, Yale University, New Haven, CT 06520-8124 (United States)

    2014-08-15

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low as 17–18M{sub ⊙} (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M{sub ⊙}, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear inputs to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector of the {sup 12}C(α,γ){sup 16}O reaction that determines the C/O ratio in stellar helium burning.

  2. Nuclear structure research with the Penning-trap mass spectrometer ISOLTRAP at CERN

    Energy Technology Data Exchange (ETDEWEB)

    Neidherr, Dennis [Johannes Gutenberg-Universitaet, Mainz (Germany)

    2009-07-01

    At the double-Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN the cyclotron frequency of short-lived radionuclides is measured in order to determine their mass with a relative uncertainty in the order of 10{sup -8} and below. This ground state property plays an important role in many fields of modern physics from nuclear-structure research to nuclear astrophysics and tests of the weak interaction of the Standard Model. An example for the first one is the evolution of the nuclear shape as a function of the number of neutrons and protons. In 2008 the masses of {sup 223-229}Rn and {sup 143-146}Xe were measured for the first time directly, whereas {sup 229}Rn was even discovered by our Penning trap based experiment. With this mass values one can study the proton-neutron interaction and therefore get information about the nuclear structure like collectivity, the onset of deformation or the geometrical shapes in atomic nuclei. The experimental results as well as the impact on the theoretical models will be presented.

  3. Nuclear Structure and the Fate of Core Collapse (Type II) Supernova

    CERN Document Server

    Gai, Moshe

    2014-01-01

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low a 17-18M$_\\odot$ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M$_\\odot$, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear input to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector the 12C(a,g)16O reaction that determines the C/O rat...

  4. Nuclear medicine department activity facing major public health challenges in France; Activite des services de medecine nucleaire face aux grands enjeux de sante publique en France

    Energy Technology Data Exchange (ETDEWEB)

    Baulieu, J.L. [Hopital Bretonneau, CHU de Tours, Unite de Medecine Nucleaire, 37 - Tours (France); Mundler, O. [CHU la Timone, Service Central de Biophysique et Medecine Nucleaire, 13 - Marseille (France)

    2007-12-15

    A national survey was made at the 2008 la Baule Symposium 'nuclear medicine facing major public health challenges'. The aim was to evaluate the activity in the fields of clinical specialities involved in these challenges : cancerology, cardiology and neurology. The response rate was 62%. The total number of PET scans performed in France during the year 2007 was about 100,000 including 97.5% of cancer indications. The mean number of PET scans per center was 1285, with a maximum of 3500 scans. The first indications were lung cancer (27%), lymphoma (20%) and colorectal cancer (14%). The registered number of cardiac examinations was 170,387 extrapolated to a total number of about 250,000 examinations in one year. The number of registered brain SPECT was 11,215 corresponding to about 100 examinations per center in one year. The survey pointed out large variations of PET activity between centers and suggested potentialities in extending and diversifying the field of PET. Brain scintigraphy appeared as a minor sector out of proportion with the challenge of degenerative brain pathology. Performing again these evaluations in the next years should allow to better describe the capabilities of nuclear medicine to face the major challenges and the evolution of public health.

  5. Research and development of earthquake-resistant structure model for nuclear fuel facility

    Energy Technology Data Exchange (ETDEWEB)

    Uryu, Mitsuru; Terada, S.; Shioya, I. [and others

    1999-05-01

    It is important for a nuclear fuel facility to reduce an input intensity of earthquake on the upper part of the building. To study of a response of the building caused by earthquake, an earthquake-resistant structure model is constructed. The weight of the structure model is 90 ton, and is supported by multiple layers of natural ruber and steel. And a weight support device which is called 'softlanding' is also installed to prevent the structure model from loosing the function at excess deformation. The softlanding device consists of Teflon. Dynamic response characteristics of the structure model caused by sine wave and simulated seismic waves are measured and analyzed. Soil tests of the fourth geologic stratum on which the structure model is sited are made to confirm the safety of soil-structure interactions caused by earthquake. (M. Suetake)

  6. Elastomeric Structural Attachment Concepts for Aircraft Flap Noise Reduction - Challenges and Approaches to Hyperelastic Structural Modeling and Analysis

    Science.gov (United States)

    Sreekantamurthy, Thammaiah; Turner, Travis L.; Moore, James B.; Su, Ji

    2014-01-01

    Airframe noise is a significant part of the overall noise of transport aircraft during the approach and landing phases of flight. Airframe noise reduction is currently emphasized under the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) Project goals of NASA. A promising concept for trailing-edge-flap noise reduction is a flexible structural element or link that connects the side edges of the deployable flap to the adjacent main-wing structure. The proposed solution is distinguished by minimization of the span-wise extent of the structural link, thereby minimizing the aerodynamic load on the link structure at the expense of increased deformation requirement. Development of such a flexible structural link necessitated application of hyperelastic materials, atypical structural configurations and novel interface hardware. The resulting highly-deformable structural concept was termed the FLEXible Side Edge Link (FLEXSEL) concept. Prediction of atypical elastomeric deformation responses from detailed structural analysis was essential for evaluating feasible concepts that met the design constraints. The focus of this paper is to describe the many challenges encountered with hyperelastic finite element modeling and the nonlinear structural analysis of evolving FLEXSEL concepts. Detailed herein is the nonlinear analysis of FLEXSEL concepts that emerged during the project which include solid-section, foamcore, hollow, extended-span and pre-stressed concepts. Coupon-level analysis performed on elastomeric interface joints, which form a part of the FLEXSEL topology development, are also presented.

  7. IMPACT OF ENERGY GROUP STRUCTURE ON NUCLEAR DATA TARGET ACCURACY REQUIREMENTS FOR ADVANCED REACTOR SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    G. Palmiotti; M. Salvatores; H. Hiruta

    2011-06-01

    A target accuracy assessment study using both a fine and a broad energy structure has shown that less stringent nuclear data accuracy requirements are needed for the latter energy structure. However, even though a reduction is observed, still the requirements will be very difficult to be met unless integral experiments are also used to reduce nuclear data uncertainties. Target accuracy assessment is the inverse problem of the uncertainty evaluation. To establish priorities and target accuracies on data uncertainty reduction, a formal approach can be adopted by defining target accuracy on design parameters and finding out required accuracy on data in order to meet them. In fact, the unknown uncertainty data requirements can be obtained by solving a minimization problem where the sensitivity coefficients in conjunction with the constraints on the integral parameters provide the needed quantities for finding the solutions.

  8. Nuclear structure of elements with 100 ≤ Z ≤ 109 from alpha spectroscopy

    Science.gov (United States)

    Asai, M.; Heßberger, F. P.; Lopez-Martens, A.

    2015-12-01

    Significant technical progress concerning the availability of intense heavy-ion beams and highly-efficient and sophisticated detection devices has made nuclear-structure investigations possible in the region of superheavy nuclei. Exciting new results have been obtained by applying α spectroscopy as well as α-γ and internal-conversion-electron coincidence spectroscopy. The present review article gives an overview of the experimental techniques and methods with specific attention to the recent developments of digital signal and data processing giving access to half-life ranges of less than a few microseconds. The presentation of the experimental results and the physics discussion will be focused on nuclear structure systematics in even-Z nuclei along the N = 151 , 153 ,and 155 isotonic lines, where most progress has been achieved in the last 10 years.

  9. Nuclear medium effects in structure functions of nucleon at moderate $Q^2$

    CERN Document Server

    Haider, H; Athar, M Sajjad; Singh, S K; Simo, I Ruiz

    2015-01-01

    Recent experiments performed on inclusive electron scattering from nuclear targets have measured the nucleon electromagnetic structure functions $F_1(x,Q^2)$, $F_2(x,Q^2)$ and $F_L(x,Q^2)$ in $^{12}C$, $^{27}Al$, $^{56}Fe$ and $^{64}Cu$ nuclei. The measurements have been done in the energy region of $1 GeV^2 < W^2 < 4 GeV^2$ and $Q^2$ region of $0.5 GeV^2 < Q^2 < 4.5 GeV^2$. We have calculated nuclear medium effects in these structure functions arising due to the Fermi motion, binding energy, nucleon correlations, mesonic contributions from pion and rho mesons and shadowing effects. The calculations are performed in a local density approximation using relativistic nucleon spectral function which include nucleon correlations. The numerical results are compared with the recent experimental data from JLab and also with some earlier experiments.

  10. Summary Report of a Specialized Workshop on Nuclear Structure and Decay Data (NSDD) Evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, Alan L. [Univ. of Surrey, Guildford (United Kingdom); Dimitrious, P. [IAEA Nuclear Data Section, Vienna (Austria); Kondev, F. G. [Argonne National Lab. (ANL), Argonne, IL (United States); Ricard-McCutchan, E. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-04-27

    A three-day specialised workshop on Nuclear Structure and Decay Data Evaluations was organised and held at the headquarters of the International Atomic Energy Agency in Vienna, Austria, from 27 to 29 April 2015. This workshop covered a wide range of important topics and issues addressed when evaluating and maintaining the Evaluated Nuclear Structure Data File (ENSDF). The primary aim was to improve evaluators’ abilities to identify and understand the most appropriate evaluation processes to adopt in the formulation of individual ENSDF data sets. Participants assessed and reviewed existing policies, procedures and codes, and round-table discussions included the debate and resolution of specific difficulties experienced by ENSDF evaluators (i.e., all workshop participants). The contents of this report constitute a record of this workshop, based on the presentations and subsequent discussions.

  11. Final disposal of spent nuclear fuel in Sweden. Some unresolved issues and challenges in the design and implementation of the forthcoming planning and EIA processes

    Energy Technology Data Exchange (ETDEWEB)

    Bjarnadottir, H.; Hilding-Rydevik, T. [Nordregio, Stockholm (Sweden)

    2001-06-01

    The aim of the study is to highlight some unresolved and challenging issues in the forthcoming approximately six year long Environmental Impact Assessment (EIA) and planning process of the long-term disposal of spent nuclear fuel in Sweden. Different international and Nordic experiences of the processes for final disposal as well as from other development of similar scope, where experiences assumed to be of importance for final disposal of nuclear waste, have been described. Furthermore, issues relating to 'good EIA practice' as well as certain aspects of planning theory have also been presented. The current Swedish situation for the planning and EIA process of the final disposal of spent nuclear fuel was also been summarized. These different 'knowledge areas' have been compared and measured against our perception of the expectations towards the forthcoming process, put forward by different Swedish actors in the field. The result is a presentation of a number of questions and identification issues that the authors consider need special attention in the design and conduction of the planning and EIA process. The study has been realized through a literature survey and followed by reading and analysis of the written material. The main focus of the literature search was on material describing planning processes, actor perspectives and EIA. Material and literature on the technical and scientific aspects of spent nuclear fuel disposal was however deliberately avoided. There is a wealth of international and Swedish literature concerning final disposal of spent nuclear fuel - concerning both technical issues and issues concerning for example public participation and risk perception. But material of a more systematic and comparative nature (relating to both empirical and theoretical issues, and to practical experiences) in relation to EIA processes and communicative planning for final disposal of spent nuclear fuel seems to be more sparsely represented

  12. A Structural Investigation into Oct4 Regulation by Orphan Nuclear Receptors, Germ Cell Nuclear Factor (GCNF) and Liver Receptor Homolog-1 (LRH-1).

    Science.gov (United States)

    Weikum, Emily R; Tuntland, Micheal L; Murphy, Michael N; Ortlund, Eric A

    2016-10-27

    Oct4 is a transcription factor required for maintaining pluripotency and self-renewal in stem cells. Prior to differentiation, Oct4 must be silenced to allow for the development of the three germ layers in the developing embryo. This fine-tuning is controlled by the nuclear receptors, liver receptor homolog-1 and germ cell nuclear factor. Liver receptor homolog-1 is responsible for driving the expression of Oct4 where germ cell nuclear factor represses its expression upon differentiation. Both receptors bind to a DR0 motif located within the Oct4 promoter. Here, we present the first structure of mouse germ cell nuclear factor DNA binding domain in complex with the Oct4 DR0. The overall structure revealed two molecules bound in a head-to-tail fashion on opposite sides of the DNA. Additionally, we solved the structure of the human liver receptor homolog-1 DNA binding domain bound to the same element. We explore the structural elements that govern Oct4 recognition by these two nuclear receptors.

  13. STRUCTURAL CALCULATIONS FOR THE CODISPOSAL OF TRIGA SPENT NUCLEAR FUEL IN A WASTE PACKAGE

    Energy Technology Data Exchange (ETDEWEB)

    S. Mastilovic

    1999-07-28

    The purpose of this analysis is to determine the structural response of a TRIGA Department of Energy (DOE) spent nuclear fuel (SNF) codisposal canister placed in a 5-Defense High Level Waste (DHLW) waste package (WP) and subjected to a tipover design basis event (DBE) dynamic load; the results will be reported in terms of displacements and stress magnitudes. This activity is associated with the WP design.

  14. Invalidity of Geometrical Interpretation of F-Spin Structure of Nuclear Rotations by Otsuka's View

    Science.gov (United States)

    Long, Guilu

    1995-06-01

    In Otsuka's view of nuclear rotations neutrons and protons are not rotating around a common axis, but rather around separate axis. In this letter, we pointed out that this invalidates the geometrical interpretation of F-spin structure of the neutron-proton interacting boson model, where the angle between the axis of symmetries of neutron ellipsoid and proton ellipsoid is used to determine whether a state is F-spin symmetric or mixed symmetric.

  15. Study for Nuclear Structures of 22-35Na Isotopes via Measurements of Reaction Cross Sections

    Science.gov (United States)

    Suzuki, Shinji

    2014-09-01

    T. Ohtsubo, M. Nagashima, T. Ogura, Y. Shimbara (Grad. Sch. of Sc., Niigata Univ.), M.Takechi, H. Geissel, M. Winkler (GSI), D. Nishimura, T. Sumikama (Dept. of Phys., Tokyo Univ. of Sc.), M. Fukuda, M. Mihara, H. Uenishi (Dept. of Phys., Osaka Univ.), T. Kuboki, T. Suzuki, T. Yamaguchi, H. Furuki, C. S. Lee, K. Sato (Dept. of Phys., Saitama Univ.), A. Ozawa, H. Ohnishi, T. Moriguchi, S. Fukuda, Y. Ishibashi, D. Nagae, R. Nishikiori, T. Niwa (Inst. of Phys., Univ. of Tsukuba), N. Aoi (RCNP), Rui-Jiu Chen, N. Inabe, D. Kameda, T. Kubo, M. Lantz, T. Ohnishi, K. Okumura, H. Sakurai, H. Suzuki, H. Takeda, S. Takeuchi, K. Tanaka, Y. Yanagisawa (RIKEN), De-Qing Fang, Yu-Gang Ma (SINAP), T. Izumikawa (RI Ctr., Niigata Univ.), and S. Momota (Fac. of Engn., Kochi Univ. of Tech.) Reaction cross sections (σR) for 22-35Na isotopes have been measured at around 240 MeV/nucleon. The σR for 22-35Na were measured for the first time. Enhancement in cross sections is clearly observed from the systematics for stable nuclei, for isotopes with large mass numbers. These enhancement can be mainly ascribed to the nuclear deformation. We will discuss the nuclear structure (neutron skin, nuclear shell structure) for neutron-excess Na isotopes. T. Ohtsubo, M. Nagashima, T. Ogura, Y. Shimbara (Grad. Sch. of Sc., Niigata Univ.), M.Takechi, H. Geissel, M. Winkler (GSI), D. Nishimura, T. Sumikama (Dept. of Phys., Tokyo Univ. of Sc.), M. Fukuda, M. Mihara, H. Uenishi (Dept. of Phys., Osaka Univ.), T. Kuboki, T. Suzuki, T. Yamaguchi, H. Furuki, C. S. Lee, K. Sato (Dept. of Phys., Saitama Univ.), A. Ozawa, H. Ohnishi, T. Moriguchi, S. Fukuda, Y. Ishibashi, D. Nagae, R. Nishikiori, T. Niwa (Inst. of Phys., Univ. of Tsukuba), N. Aoi (RCNP), Rui-Jiu Chen, N. Inabe, D. Kameda, T. Kubo, M. Lantz, T. Ohnishi, K. Okumura, H. Sakurai, H. Suzuki, H. Takeda, S. Takeuchi, K. Tanaka, Y. Yanagisawa (RIKEN), De-Qing Fang, Yu-Gang Ma (SINAP), T. Izumikawa (RI Ctr., Niigata Univ.), and S. Momota (Fac. of Engn

  16. Approach to the E-ELT dome and main structure challenges

    Science.gov (United States)

    Bilbao, Armando; Murga, Gaizka; Gómez, Celia; Llarena, Javier

    2014-07-01

    The E-ELT as a whole could be classified as an extremely challenging project. More precisely, it should be defined as an array of many different sub-challenges, which comprise technical, logistical and managerial matters. This paper reviews some of these critical challenges, in particular those related to the Dome and the Main Structure, suggesting ways to face them in the most pragmatic way possible. Technical challenges for the Dome and the Main Structure are mainly related to the need to upscale current design standards to an order of magnitude larger design. Trying a direct design escalation is not feasible; it would not work. A design effort is needed to cross hybridize current design standards with technologies coming from other different applications. Innovative design is therefore not a wish but a must. And innovative design comes along with design risk. Design risk needs to be tackled from two angles: on the one hand through thorough design validation analysis and on the other hand through extensive pre-assembly and testing. And, once again, full scale integrated pre-assembly and testing of extremely large subsystems is not always possible. Therefore, defining a comprehensive test plan for critical components, critical subsystems and critical subassemblies becomes essential. Logistical challenges are linked to the erection site. Cerro Armazones is a remote site and this needs to be considered when evaluating transport and erection requirements. But it is not only the remoteness of the site that needs to be considered. The size of both Dome and Main Structure require large construction cranes and a well defined erection plan taking into account pre-assembly strategies, limited plan area utilization, erection sequence, erection stability during intermediate stages and, very specifically, efficient coordination between the Dome and the Main Structure erection processes. Managerial issues pose another set of challenges in this project. Both the size of the

  17. Research on a laser ultrasound method for testing the quality of a nuclear radiation protection structure

    Science.gov (United States)

    Zhang, Kuanshuang; Zhou, Zhenggan; Ma, Liyin

    2017-02-01

    Laser ultrasonics has been investigated for inspecting the quality of a nuclear radiation protection structure. A possibility is proposed to improve the signal to noise ratio (SNR) of a laser ultrasonic inspection system. Then, a nuclear radiation protection structure composed of an AISI 1045 steel sheet connected with a lead alloy sheet by using an epoxy resin adhesive was manufactured with simulated defects. A non-contact laser ultrasonic inspection system, where the measured signals were filtered using a wavelet threshold de-noising method, was established to conduct a series of experiments. The proposed signal processing method can significantly improve the SNR of measured laser ultrasound signals on a rough solid surface. Compared with the SNR of original ultrasonic signals measured in transmission and reflection, the SNR of processed transmitted and reflected signals is improved by 13.8 and 16.6 dB, respectively. Moreover, laser ultrasonic C-scans based on the transmission and pulse-echo method can detect the simulated de-bonding defects, and the relative deviation between the measured sizes and design values is below 9%. Therefore, the laser ultrasonic method combined with effective signal processing can achieve the quantitative characterization of de-bonding defects in nuclear radiation protection structures.

  18. The unexpected structure of the designed protein Octarellin V.1 forms a challenge for protein structure prediction tools.

    Science.gov (United States)

    Figueroa, Maximiliano; Sleutel, Mike; Vandevenne, Marylene; Parvizi, Gregory; Attout, Sophie; Jacquin, Olivier; Vandenameele, Julie; Fischer, Axel W; Damblon, Christian; Goormaghtigh, Erik; Valerio-Lepiniec, Marie; Urvoas, Agathe; Durand, Dominique; Pardon, Els; Steyaert, Jan; Minard, Philippe; Maes, Dominique; Meiler, Jens; Matagne, André; Martial, Joseph A; Van de Weerdt, Cécile

    2016-07-01

    Despite impressive successes in protein design, designing a well-folded protein of more 100 amino acids de novo remains a formidable challenge. Exploiting the promising biophysical features of the artificial protein Octarellin V, we improved this protein by directed evolution, thus creating a more stable and soluble protein: Octarellin V.1. Next, we obtained crystals of Octarellin V.1 in complex with crystallization chaperons and determined the tertiary structure. The experimental structure of Octarellin V.1 differs from its in silico design: the (αβα) sandwich architecture bears some resemblance to a Rossman-like fold instead of the intended TIM-barrel fold. This surprising result gave us a unique and attractive opportunity to test the state of the art in protein structure prediction, using this artificial protein free of any natural selection. We tested 13 automated webservers for protein structure prediction and found none of them to predict the actual structure. More than 50% of them predicted a TIM-barrel fold, i.e. the structure we set out to design more than 10years ago. In addition, local software runs that are human operated can sample a structure similar to the experimental one but fail in selecting it, suggesting that the scoring and ranking functions should be improved. We propose that artificial proteins could be used as tools to test the accuracy of protein structure prediction algorithms, because their lack of evolutionary pressure and unique sequences features.

  19. Technology Challenges and Opportunities for Very Large In-Space Structural Systems

    Science.gov (United States)

    Belvin, W. Keith; Dorsey, John T.; Watson, Judith J.

    2009-01-01

    Space solar power satellites and other large space systems will require creative and innovative concepts in order to achieve economically viable designs. The mass and volume constraints of current and planned launch vehicles necessitate highly efficient structural systems be developed. In addition, modularity and in-space deployment/construction will be enabling design attributes. While current space systems allocate nearly 20 percent of the mass to the primary structure, the very large space systems of the future must overcome subsystem mass allocations by achieving a level of functional integration not yet realized. A proposed building block approach with two phases is presented to achieve near-term solar power satellite risk reduction with accompanying long-term technology advances. This paper reviews the current challenges of launching and building very large space systems from a structures and materials perspective utilizing recent experience. Promising technology advances anticipated in the coming decades in modularity, material systems, structural concepts, and in-space operations are presented. It is shown that, together, the current challenges and future advances in very large in-space structural systems may provide the technology pull/push necessary to make solar power satellite systems more technically and economically feasible.

  20. Alterations in nuclear structure promote lupus autoimmunity in a mouse model

    Directory of Open Access Journals (Sweden)

    Namrata Singh

    2016-08-01

    Full Text Available Systemic lupus erythematosus (SLE is an autoimmune disorder characterized by the development of autoantibodies that recognize components of the cell nucleus. The vast majority of lupus research has focused on either the contributions of immune cell dysfunction or the genetics of the disease. Because granulocytes isolated from human SLE patients had alterations in neutrophil nuclear morphology that resembled the Pelger–Huet anomaly, and had prominent mis-splicing of mRNA encoding the nuclear membrane protein lamin B receptor (LBR, consistent with their Pelger–Huet-like nuclear morphology, we used a novel mouse model system to test the hypothesis that a disruption in the structure of the nucleus itself also contributes to the development of lupus autoimmunity. The lupus-prone mouse strain New Zealand White (NZW was crossed with c57Bl/6 mice harboring a heterozygous autosomal dominant mutation in Lbr (B6.Lbric/+, and the (NZW×B6.LbricF1 offspring were evaluated for induction of lupus autoimmunity. Only female (NZW×B6.LbricF1 mice developed lupus autoimmunity, which included splenomegaly, kidney damage and autoantibodies. Kidney damage was accompanied by immune complex deposition, and perivascular and tubule infiltration of mononuclear cells. The titers of anti-chromatin antibodies exceeded those of aged female MRL-Faslpr mice, and were predominantly of the IgG2 subclasses. The anti-nuclear antibody staining profile of female (NZW×B6.LbricF1 sera was complex, and consisted of an anti-nuclear membrane reactivity that colocalized with the A-type lamina, in combination with a homogeneous pattern that was related to the recognition of histones with covalent modifications that are associated with gene activation. An anti-neutrophil IgM recognizing calreticulin, but not myeloperoxidase (MPO or proteinase 3 (PR3, was also identified. Thus, alterations in nuclear structure contribute to lupus autoimmunity when expressed in the context of a lupus

  1. Alterations in nuclear structure promote lupus autoimmunity in a mouse model

    Science.gov (United States)

    Singh, Namrata; Johnstone, Duncan B.; Martin, Kayla A.; Tempera, Italo; Kaplan, Mariana J.

    2016-01-01

    ABSTRACT Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by the development of autoantibodies that recognize components of the cell nucleus. The vast majority of lupus research has focused on either the contributions of immune cell dysfunction or the genetics of the disease. Because granulocytes isolated from human SLE patients had alterations in neutrophil nuclear morphology that resembled the Pelger–Huet anomaly, and had prominent mis-splicing of mRNA encoding the nuclear membrane protein lamin B receptor (LBR), consistent with their Pelger–Huet-like nuclear morphology, we used a novel mouse model system to test the hypothesis that a disruption in the structure of the nucleus itself also contributes to the development of lupus autoimmunity. The lupus-prone mouse strain New Zealand White (NZW) was crossed with c57Bl/6 mice harboring a heterozygous autosomal dominant mutation in Lbr (B6.Lbric/+), and the (NZW×B6.Lbric)F1 offspring were evaluated for induction of lupus autoimmunity. Only female (NZW×B6.Lbric)F1 mice developed lupus autoimmunity, which included splenomegaly, kidney damage and autoantibodies. Kidney damage was accompanied by immune complex deposition, and perivascular and tubule infiltration of mononuclear cells. The titers of anti-chromatin antibodies exceeded those of aged female MRL-Faslpr mice, and were predominantly of the IgG2 subclasses. The anti-nuclear antibody staining profile of female (NZW×B6.Lbric)F1 sera was complex, and consisted of an anti-nuclear membrane reactivity that colocalized with the A-type lamina, in combination with a homogeneous pattern that was related to the recognition of histones with covalent modifications that are associated with gene activation. An anti-neutrophil IgM recognizing calreticulin, but not myeloperoxidase (MPO) or proteinase 3 (PR3), was also identified. Thus, alterations in nuclear structure contribute to lupus autoimmunity when expressed in the context of a lupus

  2. Arrangement of nuclear structures is not transmitted through mitosis but is identical in sister cells.

    Science.gov (United States)

    Orlova, Darya Yu; Stixová, Lenka; Kozubek, Stanislav; Gierman, Hinco J; Šustáčková, Gabriela; Chernyshev, Andrei V; Medvedev, Ruslan N; Legartová, Soňa; Versteeg, Rogier; Matula, Pavel; Stoklasa, Roman; Bártová, Eva

    2012-11-01

    Although it is well known that chromosomes are non-randomly organized during interphase, it is not completely clear whether higher-order chromatin structure is transmitted from mother to daughter cells. Therefore, we addressed the question of how chromatin is rearranged during interphase and whether heterochromatin pattern is transmitted after mitosis. We additionally tested the similarity of chromatin arrangement in sister interphase nuclei. We noticed a very active cell rotation during interphase, especially when histone hyperacetylation was induced or transcription was inhibited. This natural phenomenon can influence the analysis of nuclear arrangement. Using photoconversion of Dendra2-tagged core histone H4 we showed that the distribution of chromatin in daughter interphase nuclei differed from that in mother cells. Similarly, the nuclear distribution of heterochromatin protein 1β (HP1β) was not completely identical in mother and daughter cells. However, identity between mother and daughter cells was in many cases evidenced by nucleolar composition. Moreover, morphology of nucleoli, HP1β protein, Cajal bodies, chromosome territories, and gene transcripts were identical in sister cell nuclei. We conclude that the arrangement of interphase chromatin is not transmitted through mitosis, but the nuclear pattern is identical in naturally synchronized sister cells. It is also necessary to take into account the possibility that cell rotation and the degree of chromatin condensation during functionally specific cell cycle phases might influence our view of nuclear architecture.

  3. Ataxin-1 with an expanded glutamine tract alters nuclear matrix-associated structures

    DEFF Research Database (Denmark)

    Skinner, P J; Koshy, B T; Cummings, C J

    1997-01-01

    Spinocerebellar ataxia type 1 (SCA1) is one of several neurodegenerative disorders caused by an expansion of a polyglutamine tract. It is characterized by ataxia, progressive motor deterioration, and loss of cerebellar Purkinje cells. To understand the pathogenesis of SCA1, we examined.......5 microm across, whereas the expanded ataxin-1 localizes to a single approximately 2-microm structure, before the onset of ataxia. Mutant ataxin-1 localizes to a single nuclear structure in affected neurons of SCA1 patients. Similarly, COS-1 cells transfected with wild-type or mutant ataxin-1 show...

  4. Nuclear structure for the crust of neutron stars and exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Goegelein, Peter

    2007-07-01

    In this work the Skyrme Hartree-Fock and Relativistic Hartree--Fock approaches have been considered to describe the structure of nuclear systems ranging from finite nuclei, structures in the crust of neutron stars to homogeneous matter. Effects of pairing correlations and finite temperature are also taken into account. The numerical procedure in the cubic box is described for the Skyrme Hartree-Fock as well as the relativistic Hartree-Fock approach. And finally, results for the crust of neutron stars and exotic nuclei are presented and discussed. (orig.)

  5. A structural analysis on the KN-12 spent nuclear fuel transport casks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dew Hey [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of); Lee, Young Shin; Ryu, Chung Hyun; Kim, Hyun Su; Lee, Jae Hyung; Na, Jae Yun [Chungnam National Univ., Taejon (Korea, Republic of)

    2001-08-15

    In this study, safety of the spent nuclear fuel cask KN-12 which is developed in 2000 is evaluated for hypothetical accidents conditions such as free drop, puncture, fire accident and water immersion. Finite element code ABAQUS/Explicit is used to compare with safety analysis report of the GNB in which analysis is performed with LS-DYNA3D for hypothetical accident conditions. Through this study, the safety of KN-12 is evaluated by comprehensive structural analysis. The capability and technological advancement of Korean community on the analysis and structural assessment of the cask will be improved. Also people's anxiety about radioactive dangers will be eliminated.

  6. A four-scale homogenization analysis of creep of a nuclear containment structure

    Energy Technology Data Exchange (ETDEWEB)

    Tran, A.B. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Échelle, MSME UMR 8208 CNRS, 5 bd Descartes, F-77454 Marne-la-Vallée (France); EDF R and D – Département MMC Site des Renardières – Avenue des Renardières - Ecuelles, 77818 Moret sur Loing Cedex (France); Department of Applied Informatics in Construction, National University of Civil Engineering, 55 Giai Phong Road, Hai Ba Trung District, Hanoi (Viet Nam); Yvonnet, J., E-mail: julien.yvonnet@univ-paris-est.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Échelle, MSME UMR 8208 CNRS, 5 bd Descartes, F-77454 Marne-la-Vallée (France); He, Q.-C. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Échelle, MSME UMR 8208 CNRS, 5 bd Descartes, F-77454 Marne-la-Vallée (France); Toulemonde, C.; Sanahuja, J. [EDF R and D – Département MMC Site des Renardières – Avenue des Renardières - Ecuelles, 77818 Moret sur Loing Cedex (France)

    2013-12-15

    A four-scale approach is proposed to predict the creep behavior of a concrete structure. The behavior of concrete is modeled through a numerical multiscale methodology, by successively homogenizing the viscoelastic behavior at different scales, starting from the cement paste. The homogenization is carried out by numerically constructing an effective relaxation tensor at each scale. In this framework, the impact of modifying the microstructural parameters can be directly observed on the structure response, like the interaction of the creep of concrete with the prestressing tendons network, and the effects of an internal pressure which might occur during a nuclear accident.

  7. Sensing actin dynamics: Structural basis for G-actin-sensitive nuclear import of MAL

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Hidemi; Matsuura, Yoshiyuki, E-mail: matsuura.yoshiyuki@d.mbox.nagoya-u.ac.jp

    2011-10-22

    Highlights: {yields} MAL has a bipartite NLS that binds to Imp{alpha} in an extended conformation. {yields} Mutational analyses verified the functional significance of MAL-Imp{alpha} interactions. {yields} Induced folding and NLS-masking by G-actins inhibit nuclear import of MAL. -- Abstract: The coordination of cytoskeletal actin dynamics with gene expression reprogramming is emerging as a crucial mechanism to control diverse cellular processes, including cell migration, differentiation and neuronal circuit assembly. The actin-binding transcriptional coactivator MAL (also known as MRTF-A/MKL1/BSAC) senses G-actin concentration and transduces Rho GTPase signals to serum response factor (SRF). MAL rapidly shuttles between the cytoplasm and the nucleus in unstimulated cells but Rho-induced depletion of G-actin leads to MAL nuclear accumulation and activation of transcription of SRF:MAL-target genes. Although the molecular and structural basis of actin-regulated nucleocytoplasmic shuttling of MAL is not understood fully, it is proposed that nuclear import of MAL is mediated by importin {alpha}/{beta} heterodimer, and that G-actin competes with importin {alpha}/{beta} for the binding to MAL. Here we present structural, biochemical and cell biological evidence that MAL has a classical bipartite nuclear localization signal (NLS) in the N-terminal 'RPEL' domain containing Arg-Pro-X-X-X-Glu-Leu (RPEL) motifs. The NLS residues of MAL adopt an extended conformation and bind along the surface groove of importin-{alpha}, interacting with the major- and minor-NLS binding sites. We also present a crystal structure of wild-type MAL RPEL domain in complex with five G-actins. Comparison of the importin-{alpha}- and actin-complexes revealed that the binding of G-actins to MAL is associated with folding of NLS residues into a helical conformation that is inappropriate for importin-{alpha} recognition.

  8. Stressor exposure has prolonged effects on colonic microbial community structure in Citrobacter rodentium-challenged mice

    Science.gov (United States)

    Galley, Jeffrey D.; Mackos, Amy R.; Varaljay, Vanessa A.; Bailey, Michael T.

    2017-01-01

    Stressor exposure significantly affects the colonic mucosa-associated microbiota, and exacerbates Citrobacter rodentium-induced inflammation, effects that can be attenuated with probiotic Lactobacillus reuteri. This study assessed the structure of the colonic mucosa-associated microbiota in mice exposed to a social stressor (called social disruption), as well as non-stressed control mice, during challenge with the colonic pathogen C. rodentium. Mice were exposed to the social stressor or home cage control conditions for six consecutive days and all mice were challenged with C. rodentium immediately following the first exposure to the stressor. In addition, mice received probiotic L. reuteri, or vehicle as a control, via oral gavage following each stressor exposure. The stressor-exposed mice had significant differences in microbial community composition compared to non-stressed control mice. This difference was first evident following the six-cycle exposure to the stressor, on Day 6 post-C. rodentium challenge, and persisted for up to 19 days after stressor termination. Mice exposed to the stressor had different microbial community composition regardless of whether they were treated with L. reuteri or treated with vehicle as a control. These data indicate that stressor exposure affects the colonic microbiota during challenge with C. rodentium, and that these effects are long-lasting and not attenuated by probiotic L. reuteri. PMID:28344333

  9. Desafios no estudo de famílias nucleares: etapas iniciais de análise Challengers in nuclear family studies: first steps in data analysis

    Directory of Open Access Journals (Sweden)

    Cláudia Lúcia de Moraes Forjaz

    2011-12-01

    Full Text Available Os estudos em famílias nucleares possibilitam a avaliação da existência de agregação familiar numa dada característica, permitindo avaliar o quanto da variação dessa característica na população pode ser atribuída à variação genética existente entre os sujeitos. Os resultados desses estudos possibilitam a elaboração de estratégias de intervenção mais eficientes e direcionadas, além de serem o ponto de partida para estudos mais complexos de epidemiologia genética, como a identificação de genes responsáveis pela característica em análise. Nas áreas de Ciências do Desporto e Educação Física, alguns estudos têm sido realizados para verificar a existência de agregação familiar e a influência genética em traços relacionados a estados de saúde, atividade e desempenho físicos. Entretanto, esses esforços revelam-se escassos em populações lusófonas e são, praticamente inexistentes, na população brasileira. Dessa forma, o presente artigo teve como propósito abordar, de forma simples e introdutória, aspectos importantes de estudos em famílias nucleares. Para tanto, foram analisadas as duas fases iniciais dos estudos de Epidemiologia Genética, ou seja, a identificação e quantificação da agregação familiar e da heritabilidade. As diferentes etapas de análise foram exemplificadas com dados reais, coletados em famílias nucleares pertencentes a um estudo realizado na cidade de Muzambinho-MG. Espera-se que esse artigo forneça subsídios e estímulo aos pesquisadores iniciantes neste tipo de investigação.Studies with nuclear families allow the identification of familiar aggregation, as well as the estimation of how much of the variability in a characteristic might be attributed to genetic differences among subjects. Results from these studies are starting points for more complex genetic research, including the identification and relevance of candidate genes. In Sport Science, studies have analyzed the

  10. Public health activities for mitigation of radiation exposures and risk communication challenges after the Fukushima nuclear accident.

    Science.gov (United States)

    Shimura, Tsutomu; Yamaguchi, Ichiro; Terada, Hiroshi; Robert Svendsen, Erik; Kunugita, Naoki

    2015-05-01

    Herein we summarize the public health actions taken to mitigate exposure of the public to radiation after the Fukushima accident that occurred on 11 March 2011 in order to record valuable lessons learned for disaster preparedness. Evacuations from the radiation-affected areas and control of the distribution of various food products contributed to the reduction of external and internal radiation exposure resulting from the Fukushima incident. However, risk communication is also an important issue during the emergency response effort and subsequent phases of dealiing with a nuclear disaster. To assist with their healing process, sound, reliable scientific information should continue to be disseminated to the radiation-affected communities via two-way communication. We will describe the essential public health actions following a nuclear disaster for the early, intermediate and late phases that will be useful for radiological preparedness planning in response to other nuclear or radiological disasters.

  11. Needfulness and challenges of internationalisation and involvement of international environmental NGOs in University research and education: The lessons learned from nuclear waste management sector research projects

    Directory of Open Access Journals (Sweden)

    Peter Mihok

    2014-11-01

    Full Text Available Society’s perceptions of desired democratic standards in radioactive waste management sector have changed significantly in the recent two decades. The change, known also as ‘participatory turn’, can be well illustrated on the example of site selection process for a geological repository of spent nuclear fuel in the Czech Republic. Empiric evidence from this process outlines links between the roles of Governmental bodies, NGOs, research institutions and businesses in dealing with the new challenges in decision making procedures concerning spent nuclear fuel. Selected examples from the EURATOM financed research projects ARGONA, COWAM and IPPA illustrate a growing need for internationalisation and involvement of environmental NGOs in related research and education processes in a near future.

  12. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22

    Directory of Open Access Journals (Sweden)

    Masaki Kobayashi

    2017-03-01

    Full Text Available Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN. Cajal bodies (CBs, unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN proteins was reduced – a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs, also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG, and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy.

  13. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22

    Science.gov (United States)

    Kobayashi, Masaki; Chandrasekhar, Ambika; Cheng, Chu; Martinez, Jose A.; Ng, Hilarie; de la Hoz, Cristiane

    2017-01-01

    ABSTRACT Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN). Cajal bodies (CBs), unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN) proteins was reduced – a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs), also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG), and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy. PMID:28250049

  14. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22.

    Science.gov (United States)

    Kobayashi, Masaki; Chandrasekhar, Ambika; Cheng, Chu; Martinez, Jose A; Ng, Hilarie; de la Hoz, Cristiane; Zochodne, Douglas W

    2017-03-01

    Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN). Cajal bodies (CBs), unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN) proteins was reduced - a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs), also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG), and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy.

  15. Development of a seismic damage assessment program for nuclear power plant structures

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Hyun Moo; Cho, Ho Hyun; Cho, Yang Hui [Seoul National Univ., Seoul (Korea, Republic of)] (and others)

    2000-12-15

    Some of nuclear power plants operating currently in Korea have been passed about 20 years after construction. Moreover, in the case of KORI I the service year is over 20 years, so their abilities are different from initial abilities. Also, earthquake outbreak increase, our country is not safe area for earthquake. Therefore, need is to guarantee the safety of these power plant structures against seismic accident, to decide to maintain them operational and to obtain data relative to maintenance/repair. Such objectives can be reached by damage assessment using inelastic seismic analysis considering aging degradation. It appears to be more important particularly for the structure enclosing the nuclear reactor that must absolutely protect against any radioactive leakage. Actually, the tendency of the technical world, led by the OECD/NEA, BNL in the United States, CEA in France and IAEA, is to develop researches or programs to assess the seismic safety considering aging degradation of operating nuclear power plants. Regard to the above-mentioned international technical trend, a technology to establish inelastic seismic analysis considering aging degradation so as to assess damage level and seismic safety margin appears to be necessary. Damage assessment and prediction system to grasp in real-time the actual seismic resistance capacity and damage level by 3-dimensional graphic representations are also required.

  16. Development of a seismic damage assessment program for nuclear power plant structures

    Energy Technology Data Exchange (ETDEWEB)

    Koh, Hyun Moo; Cho, Yang Heui; Shin, Hyun Mok [Seoul National Univ., Seoul (Korea, Republic of)] (and others)

    2001-12-15

    The most part of the nuclear power plants operating currently in Korea are more than 20 years old and obviously we cannot pretend that their original performance is actually maintained. In addition, earthquake occurrences show an increasing trend all over the world, and Korea can no more be considered as a zone safe from earthquake. Therefore, need is to guarantee the safety of these power plant structures against seismic accident, to decide to maintain them operational and to obtain data relative to maintenance/repair. Such objectives can be reached by damage assessment using inelastic seismic analysis considering aging degradation. It appears to be more important particularly for the structure enclosing the nuclear reactor that must absolutely protect against any radioactive leakage. Actually, the tendency of the technical world, led by the OECD/NEA, BNL in the United States, CEA in France and IAEA, is to develop researches or programs to assess the seismic safety considering aging degradation of operating nuclear power plants. Regard to the above-mentioned international technical trend, a technology to establish inelastic seismic analysis considering aging degradation so as to assess damage level and seismic safety margin appears to be necessary. Damage assessment and prediction system to grasp in real-time the actual seismic resistance capacity and damage level by 3-dimensional graphic representations are also required.

  17. Molecular early main group metal hydrides: synthetic challenge, structures and applications.

    Science.gov (United States)

    Harder, Sjoerd

    2012-11-25

    Within the general area of early main group metal chemistry, the controlled synthesis of well-defined metal hydride complexes is a rapidly developing research field. As group 1 and 2 metal complexes are generally highly dynamic and lattice energies for their [MH](∞) and [MH(2)](∞) salts are high, the synthesis of well-defined soluble hydride complexes is an obvious challenge. Access to molecular early main group metal hydrides, however, is rewarding: these hydrocarbon-soluble metal hydrides are highly reactive, have found use in early main group metal catalysis and are potentially also valuable molecular model systems for polar metal hydrides as a hydrogen storage material. The article focusses specifically on alkali and alkaline-earth metal hydride complexes and discusses the synthetic challenge, molecular structures, reactivity and applications.

  18. Nuclear Scans

    Science.gov (United States)

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  19. DISCOVERY OF LATENT STRUCTURES: EXPERIENCE WITH THE COIL CHALLENGE 2000 DATA SET

    Institute of Scientific and Technical Information of China (English)

    Nevin L. ZHANG; Yi WANG; Tao CHEN

    2008-01-01

    The authors present a case study to demonstrate the possibility of discovering complex and interesting latent structures using hierarchical latent class (HLC) models. A similar effort was made earlier by Zhang (2002), but that study involved only small applications with 4 or 5 observed variables and no more than 2 latent variables due to the lack of efficient learning algorithms. Significant progress has been made since then on algorithmic research, and it is now possible to learn HLC models with dozens of observed variables. This allows us to demonstrate the benefits of HLC models more convincingly than before. The authors have successfully analyzed the CoIL Challenge 2000 data set using HLC models. The model obtained consists of 22 latent variables, and its structure is intuitively appealing. It is exciting to know that such a large and meaningful latent structure can be automatically inferred from data.

  20. Nuclear medium modification of the F{sub 2}(x,Q{sup 2}) structure function

    Energy Technology Data Exchange (ETDEWEB)

    Sajjad Athar, M., E-mail: sajathar@gmail.co [Department of Physics, Aligarh Muslim University, Aligarh 202 002 (India); Ruiz Simo, I.; Vicente Vacas, M.J. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia - CSIC, 46100 Burjassot (Valencia) (Spain)

    2011-05-01

    We study the nuclear effects in the electromagnetic structure function F{sub 2}(x,Q{sup 2}) in the deep inelastic lepton-nucleus scattering process by taking into account Fermi motion, binding, pion and rho meson cloud contributions. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations. The ratios R{sub F}{sub 2}{sup A}(x,Q{sup 2})=(2F{sub 2}{sup A}(x,Q{sup 2}))/(AF{sub 2}{sup D}(x,Q{sup 2})) are obtained and compared with recent JLab results for light nuclei with special attention to the slope of the x distributions. This magnitude shows a non-trivial A dependence and it is insensitive to possible normalization uncertainties. The results have also been compared with some of the older experiments using intermediate mass nuclei.

  1. Unified description of structure and reactions: implementing the Nuclear Field Theory program

    CERN Document Server

    Broglia, Ricardo A; Barranco, Francisco; Vigezzi, Enrico; Idini, Andrea; Potel, Gregory

    2015-01-01

    The modern theory of the atomic nucleus results from the merging of the liquid drop (Niels Bohr and Fritz Kalckar) and of the shell model (Marie Goeppert Meyer and Axel Jensen), which contributed the concepts of collective excitations and of independent-particle motion respectively. The unification of these apparently contradictory views in terms of the particle-vibration (rotation) coupling (Aage Bohr and Ben Mottelson) has allowed for an ever increasingly complete, accurate and detailed description of the nuclear structure, Nuclear Field Theory (NFT, developed by the Copenhagen-Buenos Aires collaboration) providing a powerful quantal embodiment. In keeping with the fact that reactions are not only at the basis of quantum mechanics (statistical interpretation, Max Born) , but also the specific tools to probe the atomic nucleus, NFT is being extended to deal with processes which involve the continuum in an intrinsic fashion, so as to be able to treat them on an equal footing with those associated with discret...

  2. Novel nuclear structure aspects of the O{nu}{beta}{beta}-decay

    Energy Technology Data Exchange (ETDEWEB)

    Menendez, J; Poves, A [Departamento de Fisica Teorica, and IFT, UAM-CSIC, Universidad Autonoma de Madrid, 28049-Madrid (Spain); Caurier, E; Nowacki, F, E-mail: alfredo.poves@uam.es [IPHC, IN2P3-CNRS/Universite Louis Pasteur, 67037-Strasbourg (France)

    2011-01-01

    We explore the influence of the deformation on the nuclear matrix elements of the neutrinoless double beta decay (NME), concluding that the difference in deformation -or more generally in the amount of quadrupole correlations- between parent and grand daughter nuclei quenches strongly the decay. We correlate these differences with the seniority structure of the nuclear wave functions. In this context, we examine the present discrepancies between the NME's obtained in the framework of the Interacting Shell Model and the Quasiparticle RPA. In our view, part of the discrepancy can be due to the limitations of the spherical QRPA in treating nuclei which have strong quadrupole correlations. We surmise that the NME's in a basis of generalized seniority are approximately model independent, i. e. they are 'universal'.

  3. Theoretical nuclear structure and astrophysics. Progress report for 1993--1995

    Energy Technology Data Exchange (ETDEWEB)

    Guidry, M.W.; Nazarewicz, W.; Strayer, M.R.

    1995-12-31

    This research effort is directed toward theoretical support and guidance for the developing fields of radioactive ion beam (RIB) physics, computational and nuclear astrophysics, and the interface between these disciplines. The authors are concerned both with the application of existing technologies and concepts to guide the initial RIB program, and the development of new ideas and new technologies to influence the longer-term future of nuclear structure physics and astrophysics. The authors report substantial progress in both areas. One measure of progress is publications and invited material. The research described here has led to more than 70 papers that are published, accepted, or submitted to refereed journals, and to 46 invited presentations at conferences and workshops.

  4. An Assessment of Uncertainty in Remaining Life Estimation for Nuclear Structural Materials

    Energy Technology Data Exchange (ETDEWEB)

    Ramuhalli, Pradeep; Griffin, Jeffrey W.; Fricke, Jacob M.; Bond, Leonard J.

    2012-12-01

    In recent years, several operating US light-water nuclear power reactors (LWRs) have moved to extended-life operations (from 40 years to 60 years), and there is interest in the feasibility of extending plant life to 80 years. Operating experience suggests that material degradation of structural components in LWRs (such as the reactor pressure vessel) is expected to be the limiting factor for safe operation during extended life. Therefore, a need exists for assessing the condition of LWR structural components and determining its remaining useful life (RUL). The ability to estimate RUL of degraded structural components provides a basis for determining safety margins (i.e., whether safe operation over some pre-determined time horizon is possible), and scheduling degradation management activities (such as potentially modifying operating conditions to limit further degradation growth). A key issue in RUL estimation is calculation of uncertainty bounds, which are dependent on current material state, as well as past and future stressor levels (such as time-at-temperature, pressure, and irradiation). This paper presents a preliminary empirical investigation into the uncertainty of RUL estimates for nuclear structural materials.

  5. Response of base-isolated nuclear structures to extreme earthquake shaking

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Manish, E-mail: mkumar2@buffalo.edu; Whittaker, Andrew S.; Constantinou, Michael C.

    2015-12-15

    Highlights: • Response-history analysis of nuclear structures base-isolated using lead–rubber bearings is performed. • Advanced numerical model of lead–rubber bearing is used to capture behavior under extreme earthquake shaking. • Results of response-history analysis obtained using simplified and advanced model of lead–rubber bearings are compared. • Heating of the lead core and variation in buckling load and axial stiffness affect the response. - Abstract: Seismic isolation using low damping rubber and lead–rubber bearings is a viable strategy for mitigating the effects of extreme earthquake shaking on safety-related nuclear structures. The mechanical properties of these bearings are not expected to change substantially in design basis shaking. However, under shaking more intense than design basis, the properties of the lead cores in lead–rubber bearings may degrade due to heating associated with energy dissipation, some bearings in an isolation system may experience net tension, and the compression and tension stiffness may be affected by the lateral displacement of the isolation system. The effects of intra-earthquake changes in mechanical properties on the response of base-isolated nuclear power plants (NPPs) are investigated using an advanced numerical model of a lead–rubber bearing that has been verified and validated, and implemented in OpenSees. A macro-model is used for response-history analysis of base-isolated NPPs. Ground motions are selected and scaled to be consistent with response spectra for design basis and beyond design basis earthquake shaking at the site of the Diablo Canyon Nuclear Generating Station. Ten isolation systems of two periods and five characteristic strengths are analyzed. The responses obtained using simplified and advanced isolator models are compared. Strength degradation due to heating of lead cores and changes in buckling load most significantly affect the response of the base-isolated NPP.

  6. Developing a structural health monitoring system for nuclear dry cask storage canister

    Science.gov (United States)

    Sun, Xiaoyi; Lin, Bin; Bao, Jingjing; Giurgiutiu, Victor; Knight, Travis; Lam, Poh-Sang; Yu, Lingyu

    2015-03-01

    Interim storage of spent nuclear fuel from reactor sites has gained additional importance and urgency for resolving waste-management-related technical issues. In total, there are over 1482 dry cask storage system (DCSS) in use at US plants, storing 57,807 fuel assemblies. Nondestructive material condition monitoring is in urgent need and must be integrated into the fuel cycle to quantify the "state of health", and more importantly, to guarantee the safe operation of radioactive waste storage systems (RWSS) during their extended usage period. A state-of-the-art nuclear structural health monitoring (N-SHM) system based on in-situ sensing technologies that monitor material degradation and aging for nuclear spent fuel DCSS and similar structures is being developed. The N-SHM technology uses permanently installed low-profile piezoelectric wafer sensors to perform long-term health monitoring by strategically using a combined impedance (EMIS), acoustic emission (AE), and guided ultrasonic wave (GUW) approach, called "multimode sensing", which is conducted by the same network of installed sensors activated in a variety of ways. The system will detect AE events resulting from crack (case for study in this project) and evaluate the damage evolution; when significant AE is detected, the sensor network will switch to the GUW mode to perform damage localization, and quantification as well as probe "hot spots" that are prone to damage for material degradation evaluation using EMIS approach. The N-SHM is expected to eventually provide a systematic methodology for assessing and monitoring nuclear waste storage systems without incurring human radiation exposure.

  7. Investigations into the Structure and Dynamics of Chalcogenide Glasses using High-Resolution Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Kaseman, Derrick Charles

    Chalcogenide glasses constitute an important class of materials that are sulfides, selenides or tellurides of group IV and/or V elements, namely Ge, As, P and Si with minor concentrations of other elements such as Ga, Sb, In. Because of their infrared transparency that can be tuned by changing chemistry and can be actively altered by exposure to band gap irradiation, chalcogenide glasses find use in passive and active optical devices for applications in the areas of photonics, remote sensing and memory technology. Therefore, it is important to establish predictive models of structure-property relationships for these materials for optimization of their physical properties for various applications. Structural elucidation of chalcogenide glasses is experimentally challenging and in order to make predictive structural models, structural units at both short and intermediate -range length scales must be identified and quantified. Nuclear Magnetic Resonance (NMR) spectroscopy is an element-specific structural probe that is uniquely suited for this task, but resolution and sensitivity issues have severely limited the applications of such techniques in the past. The recent development of multi-dimensional solid-state NMR techniques, such as Phase Adjusted Spinning Sidebands (PASS) and Magic Angle Turning (MAT) can potentially alleviate such issues. In this study novel two-dimensional, high-resolution 77Se and 125Te MATPASS NMR spectroscopic techniques are utilized to elucidate quantitatively the compositional evolution of the short- and intermediate- range atomic structure in three binary chalcogenide glass-forming systems, namely: GexSe100-x, AsxSe100-x , and AsxTe100-x. The spectroscopic results provide unambiguous site speciation and quantification for short- and intermediate-range structural motifs present in these glasses. In turn, for all systems, robust structural models and the corresponding structure-property relationships are successfully established as a function

  8. The nuclear higher-order structure defined by the set of topological relationships between DNA and the nuclear matrix is species-specific in hepatocytes.

    Science.gov (United States)

    Silva-Santiago, Evangelina; Pardo, Juan Pablo; Hernández-Muñoz, Rolando; Aranda-Anzaldo, Armando

    2017-01-15

    During the interphase the nuclear DNA of metazoan cells is organized in supercoiled loops anchored to constituents of a nuclear substructure or compartment known as the nuclear matrix. The stable interactions between DNA and the nuclear matrix (NM) correspond to a set of topological relationships that define a nuclear higher-order structure (NHOS). Current evidence suggests that the NHOS is cell-type-specific. Biophysical evidence and theoretical models suggest that thermodynamic and structural constraints drive the actualization of DNA-NM interactions. However, if the topological relationships between DNA and the NM were the subject of any biological constraint with functional significance then they must be adaptive and thus be positively selected by natural selection and they should be reasonably conserved, at least within closely related species. We carried out a coarse-grained, comparative evaluation of the DNA-NM topological relationships in primary hepatocytes from two closely related mammals: rat and mouse, by determining the relative position to the NM of a limited set of target sequences corresponding to highly-conserved genomic regions that also represent a sample of distinct chromosome territories within the interphase nucleus. Our results indicate that the pattern of topological relationships between DNA and the NM is not conserved between the hepatocytes of the two closely related species, suggesting that the NHOS, like the karyotype, is species-specific.

  9. Challenges, applications, and recent advances of protein-ligand docking in structure-based drug design.

    Science.gov (United States)

    Grinter, Sam Z; Zou, Xiaoqin

    2014-07-11

    The docking methods used in structure-based virtual database screening offer the ability to quickly and cheaply estimate the affinity and binding mode of a ligand for the protein receptor of interest, such as a drug target. These methods can be used to enrich a database of compounds, so that more compounds that are subsequently experimentally tested are found to be pharmaceutically interesting. In addition, like all virtual screening methods used for drug design, structure-based virtual screening can focus on curated libraries of synthesizable compounds, helping to reduce the expense of subsequent experimental verification. In this review, we introduce the protein-ligand docking methods used for structure-based drug design and other biological applications. We discuss the fundamental challenges facing these methods and some of the current methodological topics of interest. We also discuss the main approaches for applying protein-ligand docking methods. We end with a discussion of the challenging aspects of evaluating or benchmarking the accuracy of docking methods for their improvement, and discuss future directions.

  10. Challenges, Applications, and Recent Advances of Protein-Ligand Docking in Structure-Based Drug Design

    Directory of Open Access Journals (Sweden)

    Sam Z. Grinter

    2014-07-01

    Full Text Available The docking methods used in structure-based virtual database screening offer the ability to quickly and cheaply estimate the affinity and binding mode of a ligand for the protein receptor of interest, such as a drug target. These methods can be used to enrich a database of compounds, so that more compounds that are subsequently experimentally tested are found to be pharmaceutically interesting. In addition, like all virtual screening methods used for drug design, structure-based virtual screening can focus on curated libraries of synthesizable compounds, helping to reduce the expense of subsequent experimental verification. In this review, we introduce the protein-ligand docking methods used for structure-based drug design and other biological applications. We discuss the fundamental challenges facing these methods and some of the current methodological topics of interest. We also discuss the main approaches for applying protein-ligand docking methods. We end with a discussion of the challenging aspects of evaluating or benchmarking the accuracy of docking methods for their improvement, and discuss future directions.

  11. Application of X-ray Absorption Spectroscopy to the study of nuclear structural materials

    Science.gov (United States)

    Liu, Shanshan

    One of key technologies for the next generation nuclear systems are advanced materials, including high temperature structural materials, fast neutron resistance core materials and so on. Local structure determination in these systems, which often are crystallographically intractable, is critical to gaining an understanding of their properties. In this thesis, X-ray Absorption Spectroscopy (XAS), including Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES), is used to examine the geometric and electronic structure of nuclear structural materials under varying conditions. The thesis is divided into two main sections. The first examines the structural analysis of nanostructured ferritic alloys (NFA) which are dispersion strengthened by an ultra high density of Y-Ti-O enriched nano-features, resulting in remarkable high temperature creep strength and radiation damage resistance. Titanium and Yttrium K-edge XAS shows commercial alloys MA957 and J12YWT more closely resemble the as received Fe-14Cr-3W-0.4Ti (wt. %) powders, and mechanically alloyed (MA) powders with 0.25Y2O3 (wt. %). It shows that a significant fraction of substitutional Ti remains dissolved in the (BCC) ferrite matrix. In contrast, annealed powders and hot isostatic press (HIP) consolidated alloys show high temperature heat treatments shift the Y and Ti to more oxidized states that are consistent with combinations of Y2Ti2O7 and, especially, TiO. The second section describes corrosion studies of Pb with 316L stainless steel, molybdenum and spinet (MgAl2O4) at high temperature by XAS. The corrosion of fuel cladding and structural materials by liquid lead at elevated temperatures is an issue that must be considered when designing advanced nuclear systems and high-power spallation neutron targets. The results of ex-situ studies show that a Mo substrate retained a smooth and less corroded surface than 316L stainless steel sample at elevated temperature. In

  12. Structure, Dynamics, and Assembly of Filamentous Bacteriophages by Nuclear Magnetic Resonance Spectroscopy

    Science.gov (United States)

    Opella, Stanley J.; Zeri, Ana Carolina; Park, Sang Ho

    2008-05-01

    Filamentous bacteriophages serve as model systems for the development and implementation of spectroscopic methods suitable for biological supramolecular assemblies. Not only are their coat proteins small and readily prepared in the laboratory, but they also have two primary roles as membrane proteins and as the principal structural element of the virus particles. As a bacterial system, they are readily labeled with stable isotopes, and this has opened possibilities for the many nuclear magnetic resonance (NMR) studies described in this review. In particular, solid-state NMR of aligned samples has been used to determine the three-dimensional structures of both the membrane-bound forms of coat proteins in phospholipid bilayers and structural forms in virus particles, which has led to an analysis of the assembly mechanism for virus particles as they are extruded through the cell membrane.

  13. Continued stabilization of the nuclear higher-order structure of post-mitotic neurons in vivo.

    Directory of Open Access Journals (Sweden)

    Janeth Alva-Medina

    Full Text Available BACKGROUND: Cellular terminal differentiation (TD correlates with a permanent exit from the cell cycle and so TD cells become stably post-mitotic. However, TD cells express the molecular machinery necessary for cell proliferation that can be reactivated by experimental manipulation, yet it has not been reported the stable proliferation of any type of reactivated TD cells. Neurons become post-mitotic after leaving the ventricular zone. When neurons are forced to reenter the cell cycle they invariably undergo cell death. Wider evidence indicates that the post-mitotic state cannot solely depend on gene products acting in trans, otherwise mutations in the corresponding genes may lead to reentry and completion of the cell cycle in TD cells, but this has not been observed. In the interphase, nuclear DNA of metazoan cells is organized in supercoiled loops anchored to a nuclear nuclear matrix (NM. The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS. We have previously compared the NHOS of aged rat hepatocytes with that of early post-mitotic rat neurons and our results indicated that a very stable NHOS is a common feature of both senescent and post-mitotic cells in vivo. PRINCIPAL FINDINGS: In the present work we compared the NHOS in rat neurons from different post-natal ages. Our results show that the trend towards further stabilization of the NHOS in neurons continues throughout post-natal life. This phenomenon occurs in absence of overt changes in the post-mitotic state and transcriptional activity of neurons, suggesting that it is independent of functional constraints. CONCLUSIONS: Apparently the continued stabilization of the NHOS as a function of time is basically determined by thermodynamic and structural constraints. We discuss how the resulting highly stable NHOS of neurons may be the structural, non-genetic basis of their permanent and irreversible post-mitotic state.

  14. Continued Stabilization of the Nuclear Higher-Order Structure of Post-Mitotic Neurons In Vivo

    Science.gov (United States)

    Alva-Medina, Janeth; Maya-Mendoza, Apolinar; Dent, Myrna A. R.; Aranda-Anzaldo, Armando

    2011-01-01

    Background Cellular terminal differentiation (TD) correlates with a permanent exit from the cell cycle and so TD cells become stably post-mitotic. However, TD cells express the molecular machinery necessary for cell proliferation that can be reactivated by experimental manipulation, yet it has not been reported the stable proliferation of any type of reactivated TD cells. Neurons become post-mitotic after leaving the ventricular zone. When neurons are forced to reenter the cell cycle they invariably undergo cell death. Wider evidence indicates that the post-mitotic state cannot solely depend on gene products acting in trans, otherwise mutations in the corresponding genes may lead to reentry and completion of the cell cycle in TD cells, but this has not been observed. In the interphase, nuclear DNA of metazoan cells is organized in supercoiled loops anchored to a nuclear nuclear matrix (NM). The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS). We have previously compared the NHOS of aged rat hepatocytes with that of early post-mitotic rat neurons and our results indicated that a very stable NHOS is a common feature of both senescent and post-mitotic cells in vivo. Principal Findings In the present work we compared the NHOS in rat neurons from different post-natal ages. Our results show that the trend towards further stabilization of the NHOS in neurons continues throughout post-natal life. This phenomenon occurs in absence of overt changes in the post-mitotic state and transcriptional activity of neurons, suggesting that it is independent of functional constraints. Conclusions Apparently the continued stabilization of the NHOS as a function of time is basically determined by thermodynamic and structural constraints. We discuss how the resulting highly stable NHOS of neurons may be the structural, non-genetic basis of their permanent and irreversible post-mitotic state. PMID:21731716

  15. Structural integrity analysis of the degraded drywell containment at the Oyster Creek Nuclear generating station.

    Energy Technology Data Exchange (ETDEWEB)

    Petti, Jason P.

    2007-01-01

    This study examines the effects of the degradation experienced in the steel drywell containment at the Oyster Creek Nuclear Generating Station. Specifically, the structural integrity of the containment shell is examined in terms of the stress limits using the ASME Boiler and Pressure Vessel (B&PV) Code, Section III, Division I, Subsection NE, and examined in terms of buckling (stability) using the ASME B&PV Code Case N-284. Degradation of the steel containment shell (drywell) at Oyster Creek was first observed during an outage in the mid-1980s. Subsequent inspections discovered reductions in the shell thickness due to corrosion throughout the containment. Specifically, significant corrosion occurred in the sandbed region of the lower sphere. Since the presence of the wet sand provided an environment which supported corrosion, a series of analyses were conducted by GE Nuclear Energy in the early 1990s. These analyses examined the effects of the degradation on the structural integrity. The current study adopts many of the same assumptions and data used in the previous GE study. However, the additional computational recourses available today enable the construction of a larger and more sophisticated structural model.

  16. Unified description of structure and reactions: implementing the nuclear field theory program

    Science.gov (United States)

    Broglia, R. A.; Bortignon, P. F.; Barranco, F.; Vigezzi, E.; Idini, A.; Potel, G.

    2016-06-01

    The modern theory of the atomic nucleus results from the merging of the liquid drop model of Niels Bohr and Fritz Kalckar, and of the shell model of Marie Goeppert Meyer and Hans Jensen. The first model contributed the concepts of collective excitations. The second, those of independent-particle motion. The unification of these apparently contradictory views in terms of the particle-vibration and particle-rotation couplings carried out by Aage Bohr and Ben Mottelson has allowed for an ever more complete, accurate and detailed description of nuclear structure. Nuclear field theory (NFT), developed by the Copenhagen-Buenos Aires collaboration, provided a powerful quantal embodiment of this unification. Reactions are not only at the basis of quantum mechanics (statistical interpretation, Max Born), but also the specific tools to probe the atomic nucleus. It is then natural that NFT is being extended to deal with processes which involve the continuum in an intrinsic fashion, so as to be able to treat them on an equal footing with those associated with bound states (structure). As a result, spectroscopic studies of transfer to continuum states could eventually make use of the NFT rules, properly extended to take care of recoil effects. In the present contribution we review the implementation of the NFT program of structure and reactions, setting special emphasis on open problems and outstanding predictions.

  17. Assessment of modular construction for safety-related structures at advanced nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Braverman, J.; Morante, R.; Hofmayer, C.

    1997-03-01

    Modular construction techniques have been successfully used in a number of industries, both domestically and internationally. Recently, the use of structural modules has been proposed for advanced nuclear power plants. The objective in utilizing modular construction is to reduce the construction schedule, reduce construction costs, and improve the quality of construction. This report documents the results of a program which evaluated the proposed use of modular construction for safety-related structures in advanced nuclear power plant designs. The program included review of current modular construction technology, development of licensing review criteria for modular construction, and initial validation of currently available analytical techniques applied to concrete-filled steel structural modules. The program was conducted in three phases. The objective of the first phase was to identify the technical issues and the need for further study in order to support NRC licensing review activities. The two key findings were the need for supplementary review criteria to augment the Standard Review Plan and the need for verified design/analysis methodology for unique types of modules, such as the concrete-filled steel module. In the second phase of this program, Modular Construction Review Criteria were developed to provide guidance for licensing reviews. In the third phase, an analysis effort was conducted to determine if currently available finite element analysis techniques can be used to predict the response of concrete-filled steel modules.

  18. Design criteria development for the structural stability of nuclear waste repository

    Energy Technology Data Exchange (ETDEWEB)

    Yun, C. H. [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of); Yu, T. S. [Daewoo Engineering Company, Sungnam (Korea, Republic of); Ko, H. M. [Seoul National Univ., Seoul (Korea, Republic of)] (and others)

    1990-11-15

    The objective of the present project is to develop design criteria for the structural stability of rock cavity for the underground repository are defined, according to which detailed descriptions for design methodologies, design stages and stability analysis of the cavity are made. The proposed criteria can be used as a guide for the preparation of design codes which are to be established as the site condition and technical emplacement procedure are fixed. The present report first reviews basic safety requirements and criteria of the underground disposal of nuclear wastes for the establishment of design concepts and stability analysis of the rock cavity. Important factors for the design are also described by considering characteristics of the wastes and underground facilities. The present project has investigated technical aspects on the design of underground structures based on the currently established underground construction technologies, and presented a proposal for design criteria for the structural stability of the nuclear waste repository. The proposed criteria consist of general provisions, geological exploration, rock classification, design process and methods, supporting system, analyses and instrumentation.

  19. Nuclear uncertainties in the spin-dependent structure functions for direct dark matter detection

    CERN Document Server

    Cerdeno, David G; Huh, Ji-Haeng; Peiro, Miguel

    2012-01-01

    We study the effect that uncertainties in the nuclear spin-dependent structure functions have in the determination of the dark matter (DM) parameters in a direct detection experiment. We show that different nuclear models that describe the spin-dependent structure function of specific target nuclei can lead to variations in the reconstructed values of the DM mass and scattering cross-section. We propose a parametrization of the spin structure functions that allows us to treat these uncertainties as variations of three parameters, with a central value and deviation that depend on the specific nucleus. The method is illustrated for germanium and xenon detectors with an exposure of 300 kg yr, assuming a hypothetical detection of DM and studying a series of benchmark points for the DM properties. We find that the effect of these uncertainties can be similar in amplitude to that of astrophysical uncertainties, especially in those cases where the spin-dependent contribution to the elastic scattering cross-section i...

  20. A Multifaceted FISH Approach to Study Endogenous RNAs and DNAs within Native Nuclear and Cell Structure

    Science.gov (United States)

    Byron, Meg; Hall, Lisa L.; Lawrence, Jeanne B.

    2013-01-01

    Fluorescence in situ hybridization (FISH) is not a singular technique, but a battery of powerful and versatile tools to examine the distribution of endogenous genes and RNAs in precise context with each other and in relation to specific proteins or cell structures. This unit offers the details of highly sensitive and successful protocols that were initially developed largely in our lab and honed over a number of years. Our emphasis is on analysis of nuclear RNAs and DNA to address specific biological questions about nuclear structure, pre-mRNA metabolism or the role of non-coding RNAs, although cytoplasmic RNA detection is also provided and generally discussed. Multi-faceted molecular cytological approaches bring precise resolution and sensitive multi-color detection to illuminate the organization and functional roles of endogenous genes and their RNAs within the native structure of fixed cells. Solutions to several common technical pitfalls are discussed, as are cautions regarding the judicious use of digital imaging and the rigors of analyzing and interpreting complex molecular cytological results. PMID:23315927

  1. Population structure of nuclear and mitochondrial DNA variation among humpback whales in the North Pacific.

    Science.gov (United States)

    Baker, C S; Medrano-Gonzalez, L; Calambokidis, J; Perry, A; Pichler, F; Rosenbaum, H; Straley, J M; Urban-Ramirez, J; Yamaguchi, M; von Ziegesar, O

    1998-06-01

    The population structure of variation in a nuclear actin intron and the control region of mitochondrial DNA is described for humpback whales from eight regions in the North Pacific Ocean: central California, Baja Peninsula, nearshore Mexico (Bahia Banderas), offshore Mexico (Socorro Island), southeastern Alaska, central Alaska (Prince Williams Sound), Hawaii and Japan (Ogasawara Islands). Primary mtDNA haplotypes and intron alleles were identified using selected restriction fragment length polymorphisms of target sequences amplified by the polymerase chain reaction (PCR-RFLP). There was little evidence of heterogeneity in the frequencies of mtDNA haplotypes or actin intron alleles due to the year or sex composition of the sample. However, frequencies of four mtDNA haplotypes showed marked regional differences in their distributions (phi ST = 0.277; P feeding grounds were selected for additional analyses of nuclear differentiation using allelic variation at four microsatellite loci. All four loci showed significant differences in allele frequencies (overall FST = 0.043; P feeding grounds were not panmictic for nuclear or mitochondrial loci, estimates of long-term migration rates suggested that male-mediated gene flow was several-fold greater than female gene flow. These results include and extend the range and sample size of previously published work, providing additional evidence for the significance of genetic management units within oceanic populations of humpback whales.

  2. Terracentric Nuclear Fission Reactor: Background, Basis, Feasibility, Structure, Evidence, and Geophysical Implications

    CERN Document Server

    Herndon, J Marvin

    2013-01-01

    The background, basis, feasibility, structure, evidence, and geophysical implications of a naturally occurring Terracentric nuclear fission georeactor are reviewed. For a nuclear fission reactor to exist at the center of the Earth, all of the following conditions must be met: (1) There must originally have been a substantial quantity of uranium within Earth's core; (2) There must be a natural mechanism for concentrating the uranium; (3) The isotopic composition of the uranium at the onset of fission must be appropriate to sustain a nuclear fission chain reaction; (4) The reactor must be able to breed a sufficient quantity of fissile nuclides to permit operation over the lifetime of Earth to the present; (5) There must be a natural mechanism for the removal of fission products; (6) There must be a natural mechanism for removing heat from the reactor; (7) There must be a natural mechanism to regulate reactor power level, and; (8) The location of the reactor or must be such as to provide containment and prevent ...

  3. The impact of Egypt's current challenges in adopting a conservative approach in its nuclear regulations regarding population considerations

    Directory of Open Access Journals (Sweden)

    Samia Wafik Morsy

    2015-10-01

    The paper outlines chronic problems the Egyptian population is suffering from in normal country state operation. It also examines the three major nuclear accidents and looks at the roles their governments played in protecting the population by defining the urgent actions such as sheltering, evacuation, distribution of iodine tablets and relocation. It argues that because developing countries are less able to deal with emergency crises as developed countries, a conservatory factor should increase distances away from the plant in nuclear regulations and reduce population numbers near the plant designated for developing countries. It is a simple way of protecting the population in developing countries where promptness for human rights of the citizens is not very much observed because of socio economic reasons.

  4. Molecular Structure Laboratory. Fourier Transform Nuclear Magnetic Resonance (FTNMR) Spectrometer and Ancillary Instrumentation at SUNY Geneseo

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, David K [State Univ. of New York (SUNY), Geneseo, NY (United States)

    2015-12-31

    An Agilent 400-MR nuclear magnetic resonance (NMR) spectrometer and ancillary equipment were purchased, which are being used for molecular structure elucidation.  The instrumentation is housed in a pre-existing facility designed specifically for its use. This instrument package is being used to expand the research and educational efforts of the faculty and students at SUNY-Geneseo and is made available to neighboring educational institutions and business concerns.  Funds were also used for training of College personnel, maintenance of the instrumentation, and installation of the equipment.

  5. Structure of Hamiltonian Matrix and the Shape of Eigenfunctions: Nuclear Octupole Deformation Model

    Institute of Scientific and Technical Information of China (English)

    XING Yong-Zhong; LI Jun-Qing; LIU Fang; ZUO Wei

    2002-01-01

    The structure of a Hamiltonian matrix for a quantum chaotic system, the nuclear octupole deformationmodel, has been discussed in detail. The distribution of the eigenfunctions of this system expanded by the eigenstates ofa quantum integrable system is studied with the help ofgeneralized Brillouin-Wigner pcrturbation theory. The resultsshow that a significant randomness in this distribution can be observed when its classical counterpart is under the strongchaotic condition. The averaged shape of the eigenfunctions fits with the Gaussian distribution only when the effects ofthe symmetry have been removed.

  6. Emerging challenges to structural integrity technology for high-temperature applications

    Institute of Scientific and Technical Information of China (English)

    TU Shantung

    2007-01-01

    Structural integrity technology has been widely used with great success for the design, manufacture and failure prevention of modem constructions such as chemical and petrochemical plants, power generation and energy conversion systems, as well as space and oceanic exploration.The modem needs of structural integrity technology are largely attributed to the increase of service temperature of the structures that results in the efficiency improvement in energy conversion and chemical processing technologies. Besides the needs arising from large-scale high-temperature plants,the high tech developments, such as micro chemo-mechanical systems and high-power electronics, provide new challenges to structural integrity technology. The present paper summarizes the recent technical progresses in large process plants and the aviation industry, micro chemo-mechanical systems,fuel cells, high-temperature electronics, and packaging and coating technologies. The state-of-the-art of structural integrity technology for high temperature applications is reviewed.Suggestions are provided for the improvement of current design and assessment methods.

  7. NUSTART: A PC code for NUclear STructure And Radiative Transition analysis and supplementation

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, G.L.; Gardner, D.G.; Gardner, M.A.

    1990-10-01

    NUSTART is a computer program for the IBM PC/At. It is designed for use with the nuclear reaction cross-section code STAPLUS, which is a STAPRE-based CRAY computer code that is being developed at Lawrence Livermore National Laboratory. The NUSTART code was developed to handle large sets of discrete nuclear levels and the multipole transitions among these levels; it operates in three modes. The Data File Error Analysis mode analyzes an existing STAPLUS input file containing the levels and their multipole transition branches for a number of physics and/or typographical errors. The Interactive Data File Generation mode allows the user to create input files of discrete levels and their branching fractions in the format required by STAPLUS, even though the user enters the information in the (different) format used by many people in the nuclear structure field. In the Branching Fractions Calculations mode, the discrete nuclear level set is read, and the multipole transitions among the levels are computed under one of two possible assumptions: (1) the levels have no collective character, or (2) the levels are all rotational band heads. Only E1, M1, and E2 transitions are considered, and the respective strength functions may be constants or, in the case of E1 transitions, the strength function may be energy dependent. The first option is used for nuclei closed shells; the bandhead option may be used to vary the E1, M1, and E2 strengths for interband transitions. K-quantum number selection rules may be invoked if desired. 19 refs.

  8. Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

    Energy Technology Data Exchange (ETDEWEB)

    Taborda, A.; Desbrée, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM/SDI/LEDI, BP-17, 31, Avenue de la Division Leclerc, 92262 Fontenay-aux-Roses (France); Carvalho, A. [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); Chaves, P.C. [C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal); Reis, M.A., E-mail: mareis@ctn.tecnico.ulisboa.pt [IEQUALTECS, Lda, Rua Dr. Francisco Sá Carneiro, 36, 2500-065 S. Gregório CLD (Portugal); C" 2TN, Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa, EN10 km 139.7, 2685-066 Bobadela LRS (Portugal)

    2016-08-15

    Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 10{sup 3} barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing {sup 57}Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

  9. Energetic electron processes fluorescence effects for structured nanoparticles X-ray analysis and nuclear medicine applications

    Science.gov (United States)

    Taborda, A.; Desbrée, A.; Carvalho, A.; Chaves, P. C.; Reis, M. A.

    2016-08-01

    Superparamagnetic iron oxide (SPIO) nanoparticles are widely used as contrast agents for nuclear magnetic resonance imaging (MRI), and can be modified for improved imaging or to become tissue-specific or even protein-specific. The knowledge of their detailed elemental composition characterisation and potential use in nuclear medicine applications, is, therefore, an important issue. X-ray fluorescence techniques such as particle induced X-ray emission (PIXE) or X-ray fluorescence spectrometry (XRF), can be used for elemental characterisation even in problematic situations where very little sample volume is available. Still, the fluorescence coefficient of Fe is such that, during the decay of the inner-shell ionised atomic structure, keV Auger electrons are produced in excess to X-rays. Since cross-sections for ionisation induced by keV electrons, for low atomic number atoms, are of the order of 103 barn, care should be taken to account for possible fluorescence effects caused by Auger electrons, which may lead to the wrong quantification of elements having atomic number lower than the atomic number of Fe. Furthermore, the same electron processes will occur in iron oxide nanoparticles containing 57Co, which may be used for nuclear medicine therapy purposes. In the present work, simple approximation algorithms are proposed for the quantitative description of radiative and non-radiative processes associated with Auger electrons cascades. The effects on analytical processes and nuclear medicine applications are quantified for the case of iron oxide nanoparticles, by calculating both electron fluorescence emissions and energy deposition on cell tissues where the nanoparticles may be embedded.

  10. Centring radiological protection on today's global challenges in energy, climate change, environment and health--with nuclear energy playing a key role.

    Science.gov (United States)

    Saint-Pierre, Sylvain

    2011-07-01

    The climate change issue includes meeting the growing demand for electricity while reducing the impacts from energy sources. Applying carbon capture and storage technology to fossil fuel energy and increasing renewable energy pose greater challenges than increasing nuclear energy. International Energy Agency's (IEA) electricity demand of 30 000 TWh by 2030 can be met with 10 000 TWh each from renewable, nuclear and fossil fuel energy. However, the ill-imposed very strict control of tiny public exposure to ionising radiation from nuclear energy continues to pose a serious hindrance. Effort needs to be re-balanced to produce an even-handed control of public exposure with emphasis on the most significant sources (i.e. natural background radiation and medical use) and vice versa. The on-going revision of the International Atomic Energy Agency Basic Safety Standards (BSS) provides an opportunity to achieve this internationally so that national regulations can be subsequently remediated. There can be no urgency in a BSS revision that fails to encompass such perspective.

  11. A highly organized structure mediating nuclear localization of a Myb2 transcription factor in the protozoan parasite Trichomonas vaginalis.

    Science.gov (United States)

    Chu, Chien-Hsin; Chang, Lung-Chun; Hsu, Hong-Ming; Wei, Shu-Yi; Liu, Hsing-Wei; Lee, Yu; Kuo, Chung-Chi; Indra, Dharmu; Chen, Chinpan; Ong, Shiou-Jeng; Tai, Jung-Hsiang

    2011-12-01

    Nuclear proteins usually contain specific peptide sequences, referred to as nuclear localization signals (NLSs), for nuclear import. These signals remain unexplored in the protozoan pathogen, Trichomonas vaginalis. The nuclear import of a Myb2 transcription factor was studied here using immunodetection of a hemagglutinin-tagged Myb2 overexpressed in the parasite. The tagged Myb2 was localized to the nucleus as punctate signals. With mutations of its polybasic sequences, 48KKQK51 and 61KR62, Myb2 was localized to the nucleus, but the signal was diffusive. When fused to a C-terminal non-nuclear protein, the Myb2 sequence spanning amino acid (aa) residues 48 to 143, which is embedded within the R2R3 DNA-binding domain (aa 40 to 156), was essential and sufficient for efficient nuclear import of a bacterial tetracycline repressor (TetR), and yet the transport efficiency was reduced with an additional fusion of a firefly luciferase to TetR, while classical NLSs from the simian virus 40 T-antigen had no function in this assay system. Myb2 nuclear import and DNA-binding activity were substantially perturbed with mutation of a conserved isoleucine (I74) in helix 2 to proline that altered secondary structure and ternary folding of the R2R3 domain. Disruption of DNA-binding activity alone by point mutation of a lysine residue, K51, preceding the structural domain had little effect on Myb2 nuclear localization, suggesting that nuclear translocation of Myb2, which requires an ordered structural domain, is independent of its DNA binding activity. These findings provide useful information for testing whether myriad Mybs in the parasite use a common module to regulate nuclear import.

  12. Structure for Transparency in Nuclear Waste Management. Comparative Review of the Structures for Nuclear Waste Management in France, Sweden and the UK. A Report from the RISCOM II Project

    Energy Technology Data Exchange (ETDEWEB)

    Espejo, Raul [Syncho Ltd., Lincoln (United Kingdom)

    2002-11-01

    This report presents a comparison of the structures for nuclear waste management in France, Sweden and the UK. The source materials for this comparison are studies carried out in each of these countries by Syncho Ltd. over the past 5 years. The Swedish structural review was sponsored by SKI and SSI, and carried out as a pilot study during the years 1996 and 1997 as part of the RISCOM Pilot Project. The structural reviews of the British and French nuclear waste management systems have been in progress for the past two years (2001-2002) within the framework of RISCOM II, sponsored by the European Union. This report offers preliminary comparative views of the three systems. As with each of the individual studies more work and information are necessary to confirm and strengthen the findings. To set the context for this report it is important to remind the reader that the study in Sweden was undertaken 5 years ago, that the French case took place at the same time of significant structural changes in the country's nuclear waste management system and that the British case was undertaken at the same time of a far-reaching Government consultation process. In all cases the number of people interviewed was small. In summary, comparing the structures for transparency suggests that once existing channels for transparency are diagnosed, it should be possible to use benchmarks of good practice in one country to design methods to improve participation and communications in others. The framework used in this report allows making comparisons beyond factual reports of similarities or differences. An important conclusion of this report is that the democratic deficits that we experience today as citizens in all societies can be ameliorated if sufficient attention is paid to producing requisite organisations, with adequate communications, capable of bridging the gaps between the silent majorities and those experts and politicians responsible for policy decisions. It is the wisdom

  13. Challenges and Opportunities for New Protein Crystallization Strategies in Structure-Based Drug Design

    Science.gov (United States)

    Grey, Jessica; Thompson, David

    2010-01-01

    Structure-based drug design (SBDD) has emerged as a valuable pharmaceutical lead discovery tool, showing potential for accelerating the discovery process, while reducing developmental costs and boosting potencies of the drug that is ultimately selected. SBDD is a iterative, rational, lead compound sculpting process that involves both the synthesis of new derivatives and the evaluation of their binding to the target structure either through computational docking or elucidation of the target structure as a complex with the lead compound. This method heavily relies on the production of high-resolution (< 2Å) three-dimensional structures of the drug target, obtained through X-ray crystallographic analysis, in the presence or absence of the drug candidate. The lack of generalized methods for high quality crystal production is still a major bottleneck in the process of macromolecular crystallization. This review provides a brief introduction to SBDD and describes several macromolecular crystallization strategies, with an emphasis on advances and challenges facing researchers in the field today. Recent trends in the development of more universal macromolecular crystallization techniques, particularly nucleation-based techniques that are applicable to both soluble and integral membrane proteins, are also discussed. PMID:21116481

  14. International challenge to predict the impact of radioxenon releases from medical isotope production on a comprehensive nuclear test ban treaty sampling station.

    Science.gov (United States)

    Eslinger, Paul W; Bowyer, Ted W; Achim, Pascal; Chai, Tianfeng; Deconninck, Benoit; Freeman, Katie; Generoso, Sylvia; Hayes, Philip; Heidmann, Verena; Hoffman, Ian; Kijima, Yuichi; Krysta, Monika; Malo, Alain; Maurer, Christian; Ngan, Fantine; Robins, Peter; Ross, J Ole; Saunier, Olivier; Schlosser, Clemens; Schöppner, Michael; Schrom, Brian T; Seibert, Petra; Stein, Ariel F; Ungar, Kurt; Yi, Jing

    2016-06-01

    The International Monitoring System (IMS) is part of the verification regime for the Comprehensive Nuclear-Test-Ban-Treaty Organization (CTBTO). At entry-into-force, half of the 80 radionuclide stations will be able to measure concentrations of several radioactive xenon isotopes produced in nuclear explosions, and then the full network may be populated with xenon monitoring afterward. An understanding of natural and man-made radionuclide backgrounds can be used in accordance with the provisions of the treaty (such as event screening criteria in Annex 2 to the Protocol of the Treaty) for the effective implementation of the verification regime. Fission-based production of (99)Mo for medical purposes also generates nuisance radioxenon isotopes that are usually vented to the atmosphere. One of the ways to account for the effect emissions from medical isotope production has on radionuclide samples from the IMS is to use stack monitoring data, if they are available, and atmospheric transport modeling. Recently, individuals from seven nations participated in a challenge exercise that used atmospheric transport modeling to predict the time-history of (133)Xe concentration measurements at the IMS radionuclide station in Germany using stack monitoring data from a medical isotope production facility in Belgium. Participants received only stack monitoring data and used the atmospheric transport model and meteorological data of their choice. Some of the models predicted the highest measured concentrations quite well. A model comparison rank and ensemble analysis suggests that combining multiple models may provide more accurate predicted concentrations than any single model. None of the submissions based only on the stack monitoring data predicted the small measured concentrations very well. Modeling of sources by other nuclear facilities with smaller releases than medical isotope production facilities may be important in understanding how to discriminate those releases from

  15. The Nuclear Structure in Nearby Luminous Infrared Galaxies: HST NICMOS Imaging of the GOALS Sample

    CERN Document Server

    Haan, S; Armus, L; Evans, A S; Howell, J H; Mazzarella, J M; Kim, D C; Vavilkin, T; Inami, H; Sanders, D B; Petric, A; Bridge, C R; Melbourne, J L; Charmandaris, V; Diaz-Santos, T; Murphy, E J; U, V; Stierwalt, S; Marshall, J A

    2010-01-01

    We present results of Hubble Space Telescope NICMOS H-band imaging of 73 of most luminous (i.e., log[L_IR/L_0]>11.4) Infrared Galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey (GOALS). This dataset combines multi-wavelength imaging and spectroscopic data from space (Spitzer, HST, GALEX, and Chandra) and ground-based telescopes. In this paper we use the high-resolution near-infrared data to recover nuclear structure that is obscured by dust at optical wavelengths and measure the evolution in this structure along the merger sequence. A large fraction of all galaxies in our sample possess double nuclei (~63%) or show evidence for triple nuclei (~6%). Half of these double nuclei are not visible in the HST B-band images due to dust obscuration. The majority of interacting LIRGs have remaining merger timescales of 0.3 to 1.3 Gyrs, based on the projected nuclear separations and the mass ratio of nuclei. We find that the bulge luminosity surface density increases significantly along the merger sequence ...

  16. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL

    2007-02-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.

  17. Nuclear Structure Functions and Heavy Flavour Leptoproduction Off the Nucleus at Small x in Perturbative QCD

    CERN Document Server

    Armesto-Pérez, Nestor

    2001-01-01

    Nuclear structure functions and cross-sections for heavy flavour production in lepton-nucleus collisions are investigated in the low x region accessible now or in the near future. The scattering on a heavy nucleus is described by the sum of fan diagrams of BFKL pomerons, which is exact in the high-colour limit. The initial condition for the evolution at x=0.01 is taken from a saturation model, which reproduces the experimental data on the proton. The A dependence of the structure functions is well described by a power factor $A^\\alpha$, with $\\alpha$ reaching values as low as 1/2 at extremely low x. The total cross-sections for heavy flavour production reach values of the order of mb, and the corresponding transverse momentum distributions are sizeable up to transverse momenta larger than the initial large scale $\\sqrt{Q^2+4m_f^2}$.

  18. Virtual ultrasound sources for inspecting nuclear components of coarse-grained structure

    Energy Technology Data Exchange (ETDEWEB)

    Brizuela, J. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires (Argentina); Katchadjian, P.; Desimone, C.; Garcia, A. [INEND-UAENDE, Comisión Nacional de Energía Atómica, Buenos Aires (Argentina)

    2014-02-18

    This work describes an ultrasonic inspection procedure designed for verifying coarse-grained structure materials, which are commonly used on nuclear reactors. In this case, conventional phased array techniques cannot be used due to attenuating characteristics and backscattered noise from microstructures inside the material. Thus, synthetic aperture ultrasonic imaging (SAFT) is used for this approach in contact conditions. In order to increase energy transferred to the medium, synthetic transmit aperture is formed by several elements which generate a diverging wavefront equivalent to a virtual ultrasound source behind the transducer. On the other hand, the phase coherence technique has been applied to reduce more structural noise and improve the image quality. The beamforming process has been implemented over a GPU platform to reduce computing time.

  19. Structure and biochemical characterization of proliferating cellular nuclear antigen from a parasitic protozoon

    Energy Technology Data Exchange (ETDEWEB)

    Cardona-Felix, Cesar S.; Lara-Gonzalez, Samuel; Brieba, Luis G. (LNLS)

    2012-02-08

    Proliferating cellular nuclear antigen (PCNA) is a toroidal-shaped protein that is involved in cell-cycle control, DNA replication and DNA repair. Parasitic protozoa are early-diverged eukaryotes that are responsible for neglected diseases. In this work, a PCNA from a parasitic protozoon was identified, cloned and biochemically characterized and its crystal structure was determined. Structural and biochemical studies demonstrate that PCNA from Entamoeba histolytica assembles as a homotrimer that is able to interact with and stimulate the activity of a PCNA-interacting peptide-motif protein from E. histolytica, EhDNAligI. The data indicate a conservation of the biochemical mechanisms of PCNA-mediated interactions between metazoa, yeast and parasitic protozoa.

  20. ODS Steel As A Structural Material For High Temperature Nuclear Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Pouchon, M.A.; Doebeli, M.; Schelldorfer, R.; Chen, J.; Hoffelner, W.; Degueldre, C

    2005-03-01

    Oxide-dispersed-strengthened (ODS) ferritic-martensitic steels are examined as possible candidates for the structural materials to be used in the future generation of High-Temperature Gas-Cooled Nuclear Reactors, and as a replacement for alternative high-temperature materials for tubing and other structural components. ODS steels are also being considered as possible material for use in future fusion applications. Since the oxide particles serve as an interfacial pinning mechanism for moving dislocations, the creep resistance of the material is improved. However, in order to use such materials in a reactor, their behaviour under irradiation must be thoroughly examined. In this work, the effects induced by He implantation are investigated the induced swelling is measured, and the mechanical behaviour of the irradiated surface is analysed. These first tests are performed at room temperature, for which clear evidence of swelling and hardening could be observed. (author)

  1. Sternheimer free determination of the 47Ti nuclear quadrupole moment from hyperfine structure measurements

    Science.gov (United States)

    Aydin, R.; Stachowska, E.; Johann, U.; Dembczyński, J.; Unkel, P.; Ertmer, W.

    1990-12-01

    The hyperfine structure (hfs) of 12 metastable states of47Ti has been measured by laser induced fluorescence. 11 of these states have been measured additionally very precisely by a laser-rf double resonance method. Taking into account results of earlier hfs measurements, the hfs of altogether 17 fine structure states has been analyzed by the simultaneous parametrization of the one- and two-body interactions in the atomic hfs for the model space (3 d+4 s) N+2 ( N=2). This gives 16 parameters for the magnetic dipole interaction and 12 parameters for the electric quadrupole interaction. From the model space parameters, obtained from the hfs fit, the nuclear quadrupole moment Q(47Ti)=0.303(24b), has been evaluated at the first time; it is free of Sternheimer corrections up to second order.

  2. Structural insights into SUN-KASH complexes across the nuclear envelope

    Institute of Scientific and Technical Information of China (English)

    Wenjia Wang; Zhaocai Zhou; Zhubing Shi; Shi Jiao; Cuicui Chen; Huizhen Wang; Guoguang Liu; Qiang Wang; Yun Zhao; Mark I Greene

    2012-01-01

    Linker of the nucleoskeleton and the cytoskeleton (LINC) complexes are composed of SUN and KASH domaincontaining proteins and bridge the inner and outer membranes of the nuclear envelope.LINC complexes play critical roles in nuclear positioning,cell polarization and cellular stiffness.Previously,we reported the homotrimeric structure of human SUN2.We have now determined the crystal structure of the human SUN2-KASH complex.In the complex structure,the SUN domain homotrimer binds to three independent "hook"-like KASH peptides.The overall conformation of the SUN domain in the complex closely resembles the SUN domain in its apo state.A major conformational change involves the AA'-loop of KASH-bound SUN domain,which rearranges to form a mini β-sheet that interacts with the KASH peptide.The PPPT motif of the KASH domain fits tightly into a hydrophobic pocket on the homotrimeric interface of the SUN domain,which we termed the BI-pocket.Moreover,two adjacent protomers of the SUN domain homotrimer sandwich the KASH domain by hydrophobic interaction and hydrogen bonding.Mutations of these binding sites disrupt or reduce the association between the SUN and KASH domains in vitro.In addition,transfection of wild-type,but not mutant,SUN2 promotes cell migration in Ovcar-3 cells.These results provide a structural model of the LINC complex,which is essential for additional study of the physical and functional coupling between the cytoplasm and the nucleoplasm.

  3. Nuclear structure with unitarily transformed two-body plus phenomenological three-body interactions

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Anneke

    2011-02-02

    The importance of three-nucleon forces for a variety of nuclear structure phenomena is apparent in various investigations. This thesis provides a first step towards the inclusion of realistic three-nucleon forces by studying simple phenomenological threebody interactions. The Unitary Correlation Operator Method (UCOM) and the Similarity Renormalization Group (SRG) provide two different approaches to derive soft phase-shift equivalent nucleon-nucleon (NN) interactions via unitary transformations. Although their motivations are quite different the NN interactions obtained with the two methods exhibit some similarities. The application of the UCOM- or SRG-transformed Argonne V18 potential in the Hartree-Fock (HF) approximation and including the second-order energy corrections emerging from many-body perturbation theory (MBPT) reveals that the systematics of experimental ground-state energies can be reproduced by some of the interactions considering a series of closed-shell nuclei across the whole nuclear chart. However, charge radii are systematically underestimated, especially for intermediate and heavy nuclei. This discrepancy to experimental data is expected to result from neglected three-nucleon interactions. As first ansatz for a three-nucleon force, we consider a finite-range three-body interaction of Gaussian shape. Its influence on ground-state energies and charge radii is discussed in detail on the basis of HF plus MBPT calculations and shows a significant improvement in the description of experimental data. As the handling of the Gaussian three-body interaction is time-extensive, we show that it can be replaced by a regularized three-body contact interaction exhibiting a very similar behavior. An extensive study characterizes its properties in detail and confirms the improvements with respect to nuclear properties. To take into account information of an exact numerical solution of the nuclear eigenvalue problem, the No-Core Shell Model is applied to

  4. Crystal structure of the shrimp proliferating cell nuclear antigen: structural complementarity with WSSV DNA polymerase PIP-box.

    Directory of Open Access Journals (Sweden)

    Jesus S Carrasco-Miranda

    Full Text Available DNA replication requires processivity factors that allow replicative DNA polymerases to extend long stretches of DNA. Some DNA viruses encode their own replicative DNA polymerase, such as the white spot syndrome virus (WSSV that infects decapod crustaceans but still require host replication accessory factors. We have determined by X-ray diffraction the three-dimensional structure of the Pacific white leg shrimp Litopenaeus vannamei Proliferating Cell Nuclear Antigen (LvPCNA. This protein is a member of the sliding clamp family of proteins, that binds DNA replication and DNA repair proteins through a motif called PIP-box (PCNA-Interacting Protein. The crystal structure of LvPCNA was refined to a resolution of 3 Å, and allowed us to determine the trimeric protein assembly and details of the interactions between PCNA and the DNA. To address the possible interaction between LvPCNA and the viral DNA polymerase, we docked a theoretical model of a PIP-box peptide from the WSSV DNA polymerase within LvPCNA crystal structure. The theoretical model depicts a feasible model of interaction between both proteins. The crystal structure of shrimp PCNA allows us to further understand the mechanisms of DNA replication processivity factors in non-model systems.

  5. Sequence and structural analyses of nuclear export signals in the NESdb database.

    Science.gov (United States)

    Xu, Darui; Farmer, Alicia; Collett, Garen; Grishin, Nick V; Chook, Yuh Min

    2012-09-01

    We compiled >200 nuclear export signal (NES)-containing CRM1 cargoes in a database named NESdb. We analyzed the sequences and three-dimensional structures of natural, experimentally identified NESs and of false-positive NESs that were generated from the database in order to identify properties that might distinguish the two groups of sequences. Analyses of amino acid frequencies, sequence logos, and agreement with existing NES consensus sequences revealed strong preferences for the Φ1-X(3)-Φ2-X(2)-Φ3-X-Φ4 pattern and for negatively charged amino acids in the nonhydrophobic positions of experimentally identified NESs but not of false positives. Strong preferences against certain hydrophobic amino acids in the hydrophobic positions were also revealed. These findings led to a new and more precise NES consensus. More important, three-dimensional structures are now available for 68 NESs within 56 different cargo proteins. Analyses of these structures showed that experimentally identified NESs are more likely than the false positives to adopt α-helical conformations that transition to loops at their C-termini and more likely to be surface accessible within their protein domains or be present in disordered or unobserved parts of the structures. Such distinguishing features for real NESs might be useful in future NES prediction efforts. Finally, we also tested CRM1-binding of 40 NESs that were found in the 56 structures. We found that 16 of the NES peptides did not bind CRM1, hence illustrating how NESs are easily misidentified.

  6. Seismic response analysis of a nuclear reactor structure considering nonlinear soil-structure interaction

    Energy Technology Data Exchange (ETDEWEB)

    Bhaumik, Lopamudra, E-mail: lbhaumi2@illinois.edu [University of Illinois at Urbana-Champaign (United States); Raychowdhury, Prishati, E-mail: prishati@iitk.ac.in [Indian Institute of Technology Kanpur (India)

    2013-12-15

    Highlights: • Seismic response analysis of an internal shearwall of a reactor is done. • Incremental dynamic analysis is performed with 30 recorded ground motions. • Equivalent viscous damping increases up to twice when nonlinear SSI is considered. • Roof drift demand increases up to 25% upon consideration of foundation nonlinearity. • Base shear, base moment and ductility reduce up to 62%, 40%, and 35%, respectively. - Abstract: This study focuses on the seismic response analysis of an internal shearwall of a typical Indian reactor resting on a medium dense sandy silty soil, incorporating the nonlinear behavior of the soil-foundation interface. The modeling is done in an open-source finite element framework, OpenSees, where the soil-structure interaction (SSI) is modeled using a Beam-on-Nonlinear-Winkler-Foundation (BNWF) approach. Static pushover analysis and cyclic analysis are performed followed by an incremental dynamic analysis (IDA) with 30 recorded ground motions. For performing IDA, the spectral acceleration of each motion corresponding to the fundamental period, S{sub a}(T{sub 1})is incremented from 0.1 g to 1.0 g with an increment step of 0.1 g. It is observed from the cyclic analysis that the equivalent viscous damping of the system increases upto twice upon incorporation of inelastic SSI. The IDA results demonstrate that the average peak base shear, base moment and displacement ductility demand reduces as much as 62%, 40%, and 35%, respectively, whereas the roof drift demand increases up to 25% upon consideration of foundation nonlinearity for the highest intensity motion. These observations indicate the need of critical consideration of nonlinear soil-structure interaction as any deficient modeling of the same may lead to an inaccurate estimation of the seismic demands of the structure.

  7. Structural basis of nucleic acid recognition by FK506-binding protein 25 (FKBP25), a nuclear immunophilin.

    Science.gov (United States)

    Prakash, Ajit; Shin, Joon; Rajan, Sreekanth; Yoon, Ho Sup

    2016-04-01

    The nuclear immunophilin FKBP25 interacts with chromatin-related proteins and transcription factors and is suggested to interact with nucleic acids. Currently the structural basis of nucleic acid binding by FKBP25 is unknown. Here we determined the nuclear magnetic resonance (NMR) solution structure of full-length human FKBP25 and studied its interaction with DNA. The FKBP25 structure revealed that the N-terminal helix-loop-helix (HLH) domain and C-terminal FK506-binding domain (FKBD) interact with each other and that both of the domains are involved in DNA binding. The HLH domain forms major-groove interactions and the basic FKBD loop cooperates to form interactions with an adjacent minor-groove of DNA. The FKBP25-DNA complex model, supported by NMR and mutational studies, provides structural and mechanistic insights into the nuclear immunophilin-mediated nucleic acid recognition.

  8. Structural determination of importin alpha in complex with beak and feather disease virus capsid nuclear localization signal

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Edward I. [Charles Sturt University, School of Animal and Veterinary Sciences, Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); EH Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); Dombrovski, Andrew K. [Charles Sturt University, School of Biomedical Sciences, Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); Swarbrick, Crystall M.D. [Charles Sturt University, School of Biomedical Sciences, Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); EH Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); Raidal, Shane R. [Charles Sturt University, School of Animal and Veterinary Sciences, Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); EH Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); Forwood, Jade K., E-mail: jforwood@csu.edu.au [Charles Sturt University, School of Biomedical Sciences, Boorooma St., Wagga Wagga, New South Wales 2678 (Australia); EH Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Boorooma St., Wagga Wagga, New South Wales 2678 (Australia)

    2013-09-06

    Highlights: •Circovirus capsid proteins contain large nuclear localization signals (NLS). •A method of nuclear import has not been elucidated. •Beak and feather disease virus (BFDV) capsid NLS was crystallized with importin α. •The structure showed BFDV NLS binding to the major site of importin α. •Result shows implications for mechanism of nuclear transport for all circoviruses. -- Abstract: Circoviruses represent a rapidly increasing genus of viruses that infect a variety of vertebrates. Replication requires shuttling viral molecules into the host cell nucleus, a process facilitated by capsid-associated protein (Cap). Whilst a nuclear localization signal (NLS) has been shown to mediate nuclear translocation, the mode of nuclear transport remains to be elucidated. To better understand this process, beak and feather disease virus (BFDV) Cap NLS was crystallized with nuclear import receptor importin-α (Impα). Diffraction yielded structural data to 2.9 Å resolution, and the binding site on both Impα and BFDV Cap NLS were well resolved. The binding mechanism for the major site is likely conserved across circoviruses as supported by the similarity of NLSs in circovirus Caps. This finding illuminates a crucial step for infection of host cells by this viral family, and provides a platform for rational drug design against the binding interface.

  9. Genetic structure of Populus hybrid zone along the Irtysh River provides insight into plastid-nuclear incompatibility.

    Science.gov (United States)

    Zeng, Yan-Fei; Zhang, Jian-Guo; Duan, Ai-Guo; Abuduhamiti, Bawerjan

    2016-06-16

    In plants, the maintenance of species integrity despite hybridization has often been explained by the co-adaption of nuclear gene complexes. However, the interaction between plastid and nuclear sub-genomes has been underestimated. Here, we analyzed the genetic structure of a Populus alba and P. tremula hybrid zone along the Irtysh River system in the Altai region, northwest China, using both nuclear microsatellites and plastid DNA sequences. We found high interspecific differentiation, although the hybrid P. × canescens was prevalent. Bayesian inference classified most hybrids into F1, followed by a few back-crosses to P. alba, and fewer F2 hybrids and back-crosses to P. tremula, indicating a few introgressions but preference toward P. alba. When plastid haplotypes in parental species were distinct, P. × canescens carried the haplotypes of both parents, but showed significant linkage between intraspecific haplotype and nuclear genotypes at several microsatellite loci. Selection, rather than migration and assortative mating, might have contributed to such plastid-nuclear disequilibria. By removing later-generated hybrids carrying interspecific combinations of haplotype and nuclear genotypes, plastid-nuclear incompatibility has greatly limited the gene exchange between P. alba and P. tremula via backcrossing with hybrids, demonstrating a significant association between plastid haplotype and the proportion of nuclear admixture.

  10. Final disposal of spent nuclear fuel in Sweden. Some unresolved issues and challenges in the design and implementation of the forthcoming planning and EIA processes

    Energy Technology Data Exchange (ETDEWEB)

    Bjarnadottir, H.; Hilding-Rydevik, T. [Nordregio, Stockholm (Sweden)

    2001-06-01

    The aim of the study is to highlight some unresolved and challenging issues in the forthcoming approximately six year long Environmental Impact Assessment (EIA) and planning process of the long-term disposal of spent nuclear fuel in Sweden. Different international and Nordic experiences of the processes for final disposal as well as from other development of similar scope, where experiences assumed to be of importance for final disposal of nuclear waste, have been described. Furthermore, issues relating to 'good EIA practice' as well as certain aspects of planning theory have also been presented. The current Swedish situation for the planning and EIA process of the final disposal of spent nuclear fuel was also been summarized. These different 'knowledge areas' have been compared and measured against our perception of the expectations towards the forthcoming process, put forward by different Swedish actors in the field. The result is a presentation of a number of questions and identification issues that the authors consider need special attention in the design and conduction of the planning and EIA process. The study has been realized through a literature survey and followed by reading and analysis of the written material. The main focus of the literature search was on material describing planning processes, actor perspectives and EIA. Material and literature on the technical and scientific aspects of spent nuclear fuel disposal was however deliberately avoided. There is a wealth of international and Swedish literature concerning final disposal of spent nuclear fuel - concerning both technical issues and issues concerning for example public participation and risk perception. But material of a more systematic and comparative nature (relating to both empirical and theoretical issues, and to practical experiences) in relation to EIA processes and communicative planning for final disposal of spent nuclear fuel seems to be more sparsely represented

  11. Nuclear Effects in Structure Functions xF3(x, Q2) from Charge Current Neutrino Deep Inelastic Scattering

    Institute of Scientific and Technical Information of China (English)

    DUAN Chun-Gui; SHEN Peng-Nian; LI Guang-Lie

    2006-01-01

    By taking advantage of the model-independent nuclear parton distributions, the structure functions xF3(x, Q2)are calculated, in comparison with the experimental data from CCFR neutrino-nuclei charge current deep inelastic scattering. It is shown that shadowing and anti-shadowing effects occur in valence quark distributions for small and medium x regions, respectively. It is suggested that the neutrino experimental data should be employed in the future for pinning down the nuclear parton distributions.

  12. A new method of evaluating tight gas sands pore structure from nuclear magnetic resonance (NMR) logs

    Science.gov (United States)

    Xiao, Liang; Mao, Zhi-qiang; Xie, Xiu-hong

    2016-04-01

    Tight gas sands always display such characteristics of ultra-low porosity, permeability, high irreducible water, low resistivity contrast, complicated pore structure and strong heterogeneity, these make that the conventional methods are invalid. Many effective gas bearing formations are considered as dry zones or water saturated layers, and cannot be identified and exploited. To improve tight gas sands evaluation, the best method is quantitative characterizing rock pore structure. The mercury injection capillary pressure (MICP) curves are advantageous in predicting formation pore structure. However, the MICP experimental measurements are limited due to the environment and economy factors, this leads formation pore structure cannot be consecutively evaluated. Nuclear magnetic resonance (NMR) logs are considered to be promising in evaluating rock pore structure. Generally, to consecutively quantitatively evaluate tight gas sands pore structure, the best method is constructing pseudo Pc curves from NMR logs. In this paper, based on the analysis of lab experimental results for 20 core samples, which were drilled from tight gas sandstone reservoirs of Sichuan basin, and simultaneously applied for lab MICP and NMR measurements, the relationships of piecewise power function between nuclear magnetic resonance (NMR) transverse relaxation T2 time and pore-throat radius Rc are established. A novel method, which is used to transform NMR reverse cumulative curve as pseudo capillary pressure (Pc) curve is proposed, and the corresponding model is established based on formation classification. By using this model, formation pseudo Pc curves can be consecutively synthesized. The pore throat radius distribution, and pore structure evaluation parameters, such as the average pore throat radius (Rm), the threshold pressure (Pd), the maximum pore throat radius (Rmax) and so on, can also be precisely extracted. After this method is extended into field applications, several tight gas

  13. Microemulsions and Aggregation Formation in Extraction Processes for Used Nuclear Fuel: Thermodynamic and Structural Studies

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Mikael [Univ. of California, Irvine, CA (United States)

    2016-05-04

    Advanced nuclear fuel cycles rely on successful chemical separation of various elements in the used fuel. Numerous solvent extraction (SX) processes have been developed for the recovery and purification of metal ions from this used material. However, the predictability of process operations has been challenged by the lack of a fundamental understanding of the chemical interactions in several of these separation systems. For example, gaps in the thermodynamic description of the mechanism and the complexes formed will make predictions very challenging. Recent studies of certain extraction systems under development and a number of more established SX processes have suggested that aggregate formation in the organic phase results in a transformation of its selectivity and efficiency. Aggregation phenomena have consistently been interfering in SX process development, and have, over the years, become synonymous with an undesirable effect that must be prevented. This multiyear, multicollaborative research effort was carried out to study solvation and self-organization in non-aqueous solutions at conditions promoting aggregation phenomena. Our approach to this challenging topic was to investigate extraction systems comprising more than one extraction reagent where synergy of the metal ion could be observed. These systems were probed for the existence of stable microemulsions in the organic phase, and a number of high-end characterization tools were employed to elucidate the role of the aggregates in metal ion extraction. The ultimate goal was to find connections between synergy of metal ion extraction and reverse micellar formation. Our main accomplishment for this project was the expansion of the understanding of metal ion complexation in the extraction system combining tributyl phosphate (TBP) and dibutyl phosphoric acid (HDBP). We have found that for this system no direct correlation exists for the metal ion extraction and the formation of aggregates, meaning that the

  14. The challenges of replicating Western E-government Structures in Ghana

    DEFF Research Database (Denmark)

    Salifu, Fauziatu; Williams, Idongesit

    2016-01-01

    African countries , from the African Information Society Initiative forum of 1995, have been working on facilitating a centralized e-government initiative. The system of implementing e-government services road map handed down by the United Nations Economic Commission for Africa to African countries...... has been the inspiration for the institutional and operational reforms driving e-government in Africa. This paper, using the Institutional theory explores the challenges of introducing these new e-government, institutional culture into an already existing cultural relationship between African...... governments and ICTs. The paper adopts a qualitative approach in the data collection and analysis. This paper concludes that a successful western e-government structure can only succeed, if deliberate measures are taken to make sure the new institution harmonizes with the existing institutional culture...

  15. Structure-based drug design to overcome drug resistance: challenges and opportunities.

    Science.gov (United States)

    Ferreira, Rafaela S; Andricopulo, Adriano D

    2014-01-01

    Drug resistance is a common concern for the development of novel antiviral, antimicrobial and anticancer therapies. To overcome this problem, several strategies have been developed, many of which involving the theme of this review, the use of structure-based drug design (SBDD) approaches. These include the successful design of new compounds that target resistant mutant proteins, as well as the development of drugs that target multiple proteins involved in specific biochemical pathways. Finally, drug resistance can also be considered in the early stages of drug discovery, through the use of strategies to delay the development of resistance. The purpose of this brief review is to underline the usefulness of SBDD approaches based on case studies, highlighting present challenges and opportunities in drug design.

  16. The Swiss automobile industry - Situation, structure, trends, challenges and chances; Automobilindustrie Schweiz. Branchenanalyse 2008

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, A.

    2008-07-01

    This paper presented at the Swiss 2008 research conference on traffic takes a look at the situation of the Swiss automobile industry in 2008. The results of the study are presented and include figures on the automobile industry, its history, structure, turn-over, employment and its position from the international point of view. Research and development in the sector, investments and challenges faced are discussed. The products and services offered are looked at and the relevant strategies examined. The sector's competitive environment and possibilities for growth are looked at and the advantages offered by strategic partnerships and geographical location are noted. Finally, interviews with important actors in the business are presented.

  17. Views of a devil`s advocate -- Fundamental challenges to effective field theory treatments of nuclear physics

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, T.D.

    1998-04-01

    The physics goals of the effective field theory program for nuclear phenomena are outlined. It is pointed out that there are multiple schemes for implementing EFT and it is presently not clear if any of these schemes is viable. Most of the applications of effective field theory ideas have been on nucleon-nucleon scattering. It is argued that this is little more than curve fitting and that other quantities need to be calculated to test the ideas. It is shown that EFT methods work well for certain bound state properties of the deuteron electric form factor. However, it is also shown that this success depends sensitively on the fact that the majority of the probability of the deuteron`s wave function is beyond the range of the potential. This circumstance is special to the deuteron suggesting that it will be very difficult to achieve the same kinds of success for tightly bound nuclei.

  18. A NEW METHOD FOR EXTRACTING SPIN-DEPENDENT NEUTRON STRUCTURE FUNCTIONS FROM NUCLEAR DATA

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, Y.F.; Melnitchouk, W.

    2009-01-01

    High-energy electrons are currently the best probes of the internal structure of nucleons (protons and neutrons). By collecting data on electrons scattering off light nuclei, such as deuterium and helium, one can extract structure functions (SFs), which encode information about the quarks that make up the nucleon. Spin-dependent SFs, which depend on the relative polarization of the electron beam and the target nucleus, encode quark spins. Proton SFs can be measured directly from electron-proton scattering, but those of the neutron must be extracted from proton data and deuterium or helium-3 data because free neutron targets do not exist. At present, there is no reliable method for accurately determining spin-dependent neutron SFs in the low-momentum-transfer regime, where nucleon resonances are prominent and the functions are not smooth. The focus of this study was to develop a new method for extracting spin-dependent neutron SFs from nuclear data. An approximate convolution formula for nuclear SFs reduces the problem to an integral equation, for which a recursive solution method was designed. The method was then applied to recent data from proton and deuterium scattering experiments to perform a preliminary extraction of spin-dependent neutron SFs in the resonance region. The extraction method was found to reliably converge for arbitrary test functions, and the validity of the extraction from data was verifi ed using a Bjorken integral, which relates integrals of SFs to a known quantity. This new information on neutron structure could be used to assess quark-hadron duality for the neutron, which requires detailed knowledge of SFs in all kinematic regimes.

  19. RATU2. The Finnish research programme on the structural integrity of nuclear power plants. Interim report 1995 - April 1997

    Energy Technology Data Exchange (ETDEWEB)

    Solin, J.; Sarkimo, M.; Asikainen, M. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity] [eds.

    1997-06-01

    The projects within the Finnish public funded research programme on the structural integrity of nuclear power plants (RATU2) are briefly introduced and the scientific and technical results obtained during the first two years, 1995-April 1997, are summarised in this report. The RATU2 programme was started in 1995 and will be continued until 1998. In 1996 this programme represented 6 % of the nuclear energy R and D in Finland. The research programme is mainly publicly funded and supplies impartial expertise for the regulation of nuclear energy. It also plays an important role in the education of new experts, technology transfer and international exchange of scientific results. The programme is organised into five research projects on the following topics: Material degradation in the reactor environment, Reliability of nondestructive inspections of nuclear power plants, Structural analyses for nuclear power plant components, Maintenance strategies and dependability, and Fire safety. The ageing of the structures and components in the Finnish nuclear power plants is one of the main issues to be considered when safety and economic operation of the plants is evaluated. At the same time, ways are being sought to extend the lifetime of components. The first half of the RATU2 research programme has already brought significant scientific findings and useful applications for ensuring the reliability of NPP components. New technology has been transferred to domestic use through active participation to international co-operation. On the other hand, international acceptance of the results has provided valuable feedback and benchmarking. (orig.). 112 refs.

  20. NRLiSt BDB, the manually curated nuclear receptors ligands and structures benchmarking database.

    Science.gov (United States)

    Lagarde, Nathalie; Ben Nasr, Nesrine; Jérémie, Aurore; Guillemain, Hélène; Laville, Vincent; Labib, Taoufik; Zagury, Jean-François; Montes, Matthieu

    2014-04-10

    Nuclear receptors (NRs) constitute an important class of drug targets. We created the most exhaustive NR-focused benchmarking database to date, the NRLiSt BDB (NRs ligands and structures benchmarking database). The 9905 compounds and 339 structures of the NRLiSt BDB are ready for structure-based and ligand-based virtual screening. In the present study, we detail the protocol used to generate the NRLiSt BDB and its features. We also give some examples of the errors that we found in ChEMBL that convinced us to manually review all original papers. Since extensive and manually curated experimental data about NR ligands and structures are provided in the NRLiSt BDB, it should become a powerful tool to assess the performance of virtual screening methods on NRs, to assist the understanding of NR's function and modulation, and to support the discovery of new drugs targeting NRs. NRLiSt BDB is freely available online at http://nrlist.drugdesign.fr .

  1. Structural Analyses of the Support Trusses for the Nuclear Thermal Rocket Engines and Drop Tanks

    Science.gov (United States)

    Myers, David E.; Kosareo, Daniel N.

    2006-01-01

    Finite element structural analyses were performed on the support trusses of the Nuclear Thermal Rocket (NTR) engines and drop tanks to verify that the proper amount of mass was allocated for these components in the vehicle sizing model. The verification included a static stress analysis, a modal analysis, and a buckling analysis using the MSC/NASTRAN™ structural analysis software package. In addition, a crippling stress analysis was performed on the truss beams using a handbook equation. Two truss configurations were examined as possible candidates for the drop tanks truss while a baseline was examined for the engine support thrust structure. For the drop tanks trusses, results showed that both truss configurations produced similar results although one performed slightly better in buckling. In addition, it was shown that the mass allocated in the vehicle sizing model was adequate although the engine thrust structure may need to be modified slightly to increase its lateral natural frequency above the minimum requirement of 8 Hz that is specified in the Delta IV Payload Planners Guide.

  2. Nuclear receptor engineering based on novel structure activity relationships revealed by farnesyl pyrophosphate.

    Science.gov (United States)

    Goyanka, Ritu; Das, Sharmistha; Samuels, Herbert H; Cardozo, Timothy

    2010-11-01

    Nuclear receptors (NRs) comprise the second largest protein family targeted by currently available drugs, acting via specific ligand interactions within the ligand binding domain (LBD). Recently, farnesyl pyrophosphate (FPP) was shown to be a unique promiscuous NR ligand, activating a subset of NR family members and inhibiting wound healing in skin. The current study aimed at visualizing the unique basis of FPP interaction with multiple receptors in order to identify general structure-activity relationships that operate across the NR family. Docking of FPP to the 3D structures of the LBDs of a diverse set of NRs consistently revealed an electrostatic FPP pyrophosphate contact with an NR arginine conserved in the NR family, a hydrophobic farnesyl contact with NR helix-12 and a ligand binding pocket volume between 300 and 430 Å(3) as the minimal requirements for FPP activation of any NR. Lack of any of these structural features appears to render a given NR resistant to FPP activation. We used these structure-activity relationships to rationally design and successfully engineer several mutant human estrogen receptors that retain responsiveness to estradiol but no longer respond to FPP.

  3. The crystal structure of Haloferax volcanii proliferating cell nuclear antigen reveals unique surface charge characteristics due to halophilic adaptation

    Directory of Open Access Journals (Sweden)

    Morroll Shaun

    2009-08-01

    Full Text Available Abstract Background The high intracellular salt concentration required to maintain a halophilic lifestyle poses challenges to haloarchaeal proteins that must stay soluble, stable and functional in this extreme environment. Proliferating cell nuclear antigen (PCNA is a fundamental protein involved in maintaining genome integrity, with roles in both DNA replication and repair. To investigate the halophilic adaptation of such a key protein we have crystallised and solved the structure of Haloferax volcanii PCNA (HvPCNA to a resolution of 2.0 Å. Results The overall architecture of HvPCNA is very similar to other known PCNAs, which are highly structurally conserved. Three commonly observed adaptations in halophilic proteins are higher surface acidity, bound ions and increased numbers of intermolecular ion pairs (in oligomeric proteins. HvPCNA possesses the former two adaptations but not the latter, despite functioning as a homotrimer. Strikingly, the positive surface charge considered key to PCNA's role as a sliding clamp is dramatically reduced in the halophilic protein. Instead, bound cations within the solvation shell of HvPCNA may permit sliding along negatively charged DNA by reducing electrostatic repulsion effects. Conclusion The extent to which individual proteins adapt to halophilic conditions varies, presumably due to their diverse characteristics and roles within the cell. The number of ion pairs observed in the HvPCNA monomer-monomer interface was unexpectedly low. This may reflect the fact that the trimer is intrinsically stable over a wide range of salt concentrations and therefore additional modifications for trimer maintenance in high salt conditions are not required. Halophilic proteins frequently bind anions and cations and in HvPCNA cation binding may compensate for the remarkable reduction in positive charge in the pore region, to facilitate functional interactions with DNA. In this way, HvPCNA may harness its environment as

  4. Homogenisation method for the dynamic analysis of a complete nuclear steam generator with fluid-structure interaction

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, Jean-Francois [DCNS Propulsion-DI/STS, 44620 La Montagne (France)], E-mail: jean-francois.sigrist@dcn.fr; Broc, Daniel [CEA Saclay-DEMT/EMSI, 91191 Gif-sur-Yvette (France)

    2008-09-15

    The present paper deals with the dynamic analysis of a steam generator tube bundle with fluid-structure interaction modelling. As the coupled fluid-structure problem involves a huge number of degrees of freedom to account for the tube displacements and the fluid pressure evolutions, classical coupled method cannot be applied for industrial studies. In the present case, the three-dimensional fluid-structure problem is solved with an homogenisation method, which has been previously exposed and successfully validated for FSI modelling in a nuclear reactor [Sigrist, J.F., Broc, D., 2007a. Homogenisation method for the modal analysis of a nuclear reactor with internal structures modelling and fluid-structure interaction coupling. Nuclear Engineering and Design 237, 431-440]. Formulation of the homogenisation method for general two- and three-dimensional cases is exposed in the paper. Application to a simplified, however representative, model of an actual industrial nuclear component (steam generator) is proposed. The problem modelling, which includes tube bundle, primary and secondary fluids and pressure vessel, is performed with an engineering finite element code in which the homogenisation technique has been implemented. From the practical point of view, the analysis highlights the major fluid-structure interaction effects on the dynamic behaviour of the steam generator; from the theoretical point of view, the study demonstrates the efficiency of the homogenisation method for periodic fluid-structure problems modelling in industrial configurations.

  5. Nuclear effects and neutron structure in deeply virtual Compton scattering off 3He

    CERN Document Server

    Rinaldi, Matteo

    2014-01-01

    The study of nuclear generalized parton distributions (GPDs) could be a crucial achievement of hadronic physics since they open new ways to obtain new information on the structure of bound nucleons, in particular, to access the neutron GPDs. Here, the results of calculations of 3He GPDs in Impulse Approximation are presented. The calculation of the sum of GPDs H + E, and "tilde H", with the correct limits, will be shown. These quantities, at low momentum transfer, are largely dominated by the neutron contribution so that 3He is an ideal target for these kind of studies. Nevertheless the extraction of neutron information from future 3He data could be non trivial. A procedure, which takes into account nuclear effects encoded in IA, is presented. The calculation of H,E and "tilde H" allows also to evaluate the cross section asymmetries for deeply virtual compton scattering at Jefferson Lab kinematics. Thanks to these observations, DVCS off 3He could be an ideal process to access the neutron information in the ne...

  6. Structural Basis of Natural Promoter Recognition by a Unique Nuclear Receptor, HNF4[alpha

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Peng; Rha, Geun Bae; Melikishvili, Manana; Wu, Guangteng; Adkins, Brandon C.; Fried, Michael G.; Chi, Young-In (Kentucky)

    2010-11-09

    HNF4{alpha} (hepatocyte nuclear factor 4{alpha}) plays an essential role in the development and function of vertebrate organs, including hepatocytes and pancreatic {beta}-cells by regulating expression of multiple genes involved in organ development, nutrient transport, and diverse metabolic pathways. As such, HNF4{alpha} is a culprit gene product for a monogenic and dominantly inherited form of diabetes, known as maturity onset diabetes of the young (MODY). As a unique member of the nuclear receptor superfamily, HNF4{alpha} recognizes target genes containing two hexanucleotide direct repeat DNA-response elements separated by one base pair (DR1) by exclusively forming a cooperative homodimer. We describe here the 2.0 {angstrom} crystal structure of human HNF4{alpha} DNA binding domain in complex with a high affinity promoter element of another MODY gene, HNF1{alpha}, which reveals the molecular basis of unique target gene selection/recognition, DNA binding cooperativity, and dysfunction caused by diabetes-causing mutations. The predicted effects of MODY mutations have been tested by a set of biochemical and functional studies, which show that, in contrast to other MODY gene products, the subtle disruption of HNF4{alpha} molecular function can cause significant effects in afflicted MODY patients.

  7. Di-nucleon structures in homogeneous nuclear matter based on two- and three-nucleon interactions

    Energy Technology Data Exchange (ETDEWEB)

    Arellano, Hugo F. [University of Chile, Department of Physics - FCFM, Santiago (Chile); CEA, DAM, DIF, Arpajon (France); Isaule, Felipe [University of Chile, Department of Physics - FCFM, Santiago (Chile); Rios, Arnau [University of Surrey, Department of Physics, Faculty of Engineering and Physical Sciences, Guildford (United Kingdom)

    2016-09-15

    We investigate homogeneous nuclear matter within the Brueckner-Hartree-Fock (BHF) approach in the limits of isospin-symmetric nuclear matter (SNM) as well as pure neutron matter at zero temperature. The study is based on realistic representations of the internucleon interaction as given by Argonne v{sub 18}, Paris, Nijmegen I and II potentials, in addition to chiral N{sup 3}LO interactions, including three-nucleon forces up to N{sup 2}LO. Particular attention is paid to the presence of di-nucleon bound states structures in {sup 1}S{sub 0} and {sup 3}SD{sub 1} channels, whose explicit account becomes crucial for the stability of self-consistent solutions at low densities. A characterization of these solutions and associated bound states is discussed. We confirm that coexisting BHF single-particle solutions in SNM, at Fermi momenta in the range 0.13-0.3 fm{sup -1}, is a robust feature under the choice of realistic internucleon potentials. (orig.)

  8. Changes in nuclear structure along the Mn isotopic chain studied via charge radii

    CERN Document Server

    Heylen, H; Beerwerth, R; Billowes, J; Bissell, M L; Blaum, K; Bonnard, J; Campbell, P; Cheal, B; Goodacre, T Day; Fedorov, D; Fritzsche, S; Ruiz, R F Garcia; Geithner, W; Geppert, Ch; Gins, W; Grob, L K; Kowalska, M; Kreim, K; Lenzi, S M; Moore, I D; Maass, B; Malbrunot-Ettenauer, S; Marsh, B; Neugart, R; Neyens, G; Nortershauser, W; Otsuka, T; Papuga, J; Rossel, R; Rothe, S; Sanchez, R; Tsunoda, Y; Wraith, C; Xie, L; Yang, X F; Yordanov, D T

    2016-01-01

    The hyperfine spectra of $^{51,53-64}$Mn were measured in two experimental runs using collinear laser spectroscopy at ISOLDE, CERN. Laser spectroscopy was performed on the atomic $3d^5\\ 4s^2\\ ^{6}\\text{S}_{5/2}\\rightarrow 3d^5\\ 4s4p\\ ^{6}\\text{P}_{3/2}$ and ionic $3d^5\\ 4s\\ ^{5}\\text{S}_2 \\rightarrow 3d^5\\ 4p\\ ^{5}\\text{P}_3$ transitions, yielding two sets of isotope shifts. The mass and field shift factors for both transitions have been calculated in the multiconfiguration Dirac-Fock framework and were combined with a King plot analysis in order to obtain a consistent set of mean-square charge radii which, together with earlier work on neutron-deficient Mn, allow the study of nuclear structure changes from $N=25$ across $N=28$ up to $N=39$. A clear development of deformation is observed towards $N=40$, confirming the conclusions of the nuclear moments studies. From a Monte Carlo Shell Model study of the shape in the Mn isotopic chain, it is suggested that the observed development of deformation is not only d...

  9. Ab initio nuclear structure and reactions with chiral three-body forces

    Energy Technology Data Exchange (ETDEWEB)

    Langhammer, Joachim; Roth, Robert; Calci, Angelo [Institut fuer Kernphysik - Theoriezentrum, TU Darmstadt (Germany); Navratil, Petr [TRIUMF, Vancouver (Canada)

    2014-07-01

    One major ambition of ab initio nuclear theory is the description of nuclear-structure and reaction observables on equal footing. This is accomplished by combining the no-core shell model (NCSM) with the resonating-group method (RGM) to a unified ab initio approach to bound and continuum states, which is developed further to the no-core shell model with continuum (NCSMC). We present the formal developments to include three-nucleon interactions in both the NCSM/RGM and NCSMC formalism. This provides the possibility to assess the predictive power of chiral two- and three-nucleon forces in the variety of scattering observables. We study three-nucleon force effects on phase-shifts, cross sections and analyzing powers in first ab-initio studies of nucleon-{sup 4}He scattering with chiral two- and three-nucleon forces. Finally, we focus on heavier target nuclei using the NCSMC, e.g., in neutron-{sup 8}Be scattering and study the impact of the continuum on the spectrum of {sup 9}Be.

  10. Changes in nuclear structure along the Mn isotopic chain studied via charge radii

    Science.gov (United States)

    Heylen, H.; Babcock, C.; Beerwerth, R.; Billowes, J.; Bissell, M. L.; Blaum, K.; Bonnard, J.; Campbell, P.; Cheal, B.; Day Goodacre, T.; Fedorov, D.; Fritzsche, S.; Garcia Ruiz, R. F.; Geithner, W.; Geppert, Ch.; Gins, W.; Grob, L. K.; Kowalska, M.; Kreim, K.; Lenzi, S. M.; Moore, I. D.; Maass, B.; Malbrunot-Ettenauer, S.; Marsh, B.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Otsuka, T.; Papuga, J.; Rossel, R.; Rothe, S.; Sánchez, R.; Tsunoda, Y.; Wraith, C.; Xie, L.; Yang, X. F.; Yordanov, D. T.

    2016-11-01

    The hyperfine spectra of 51,53 -64Mn were measured in two experimental runs using collinear laser spectroscopy at ISOLDE, CERN. Laser spectroscopy was performed on the atomic 3 d54 s25/2 6S →3 d54 s 4 p 3/2 6P and ionic 3 d54 s 5S2→3 d54 p 5P3 transitions, yielding two sets of isotope shifts. The mass and field shift factors for both transitions have been calculated in the multiconfiguration Dirac-Fock framework and were combined with a King plot analysis in order to obtain a consistent set of mean-square charge radii which, together with earlier work on neutron-deficient Mn, allow the study of nuclear structure changes from N =25 across N =28 up to N =39 . A clear development of deformation is observed towards N =40 , confirming the conclusions of the nuclear moments studies. From a Monte Carlo shell-model study of the shape in the Mn isotopic chain, it is suggested that the observed development of deformation is not only due to an increase in static prolate deformation but also due to shape fluctuations and triaxiality. The changes in mean-square charge radii are well reproduced using the Duflo-Zuker formula except in the case of large deformation.

  11. Analytical challenges of determining composition and structure in small volumes with applications to semiconductor technology, nanostructures and solid state science

    Science.gov (United States)

    Ma, Zhiyong; Kuhn, Markus; Johnson, David C.

    2017-03-01

    Determining the structure and composition of small volumes is vital to the ability to understand and control nanoscale properties and critical for advancing both fundamental science and applications, such as semiconductor device manufacturing. While metrology of nanoscale materials (nanoparticles, nanocomposites) and nanoscale semiconductor structures is challenging, both basic research and cutting edge technology benefit from new and enhanced analytical techniques. This focus issue contains articles describing approaches to overcome the challenges in obtaining statistically significant atomic-scale quantification of structure and composition in a variety of materials and devices using electron microscopy and atom probe tomography.

  12. Overview of activities in the U.S. related to continued service of nuclear power plant concrete structures

    Directory of Open Access Journals (Sweden)

    Naus D.J.

    2011-04-01

    Full Text Available Safety-related nuclear power plant concrete structures are described and commentary on continued service assessments of these structures is provided. In-service inspection and testing requirements in the U.S. are summarized. The license renewal process in the U.S. is outlined and its current status noted. A summary of operating experience related to U.S. nuclear power plant concrete structures is presented. Several candidate areas are identified where additional research would be of benefit to aging management of NPP concrete structures. Finally current ORNL activities related to aging-management of concrete structures are outlined: development of operating experience database, application of structural reliability theory, and compilation of elevated temperature concrete material property data and information.

  13. Activities report in nuclear physics

    NARCIS (Netherlands)

    Jansen, J. F. W.; Scholten, O.

    1987-01-01

    Experimental studies of giant resonances, nuclear structure, light mass systems, and heavy mass systems are summarized. Theoretical studies of nuclear structure, and dynamics are described. Electroweak interactions; atomic and surface physics; applied nuclear physics; and nuclear medicine are discus

  14. Structural response of nuclear containment shield buildings with unanticipated construction openings

    Science.gov (United States)

    Mac Namara, Sinead Caitriona

    As Nuclear Power Plants age many require steam generator replacement. There is a nickel alloy in the steam generator tubes that is susceptible to stress cracking and although these cracks can be sealed the generator becomes uneconomical without 10%-15% of the tubes. The steam generator in a typical nuclear power plant is housed in the containment structure next to the reactor. The equipment hatch is not big enough to facilitate steam generator replacement, thus construction openings in the dome of the containment structure are required. To date the structural consequences of construction openings in the dome have not been examined. This thesis examines the effects of such openings. The prototype concrete dome is made up of a 2 ft thick dome atop 3 ft thick and 170 ft high cylindrical walls (radius 65.5 ft) with a tension ring 15 ft high and 8 ft thick in between. The dome of the building is cast in two layers; a lower 9 inch layer that serves as the formwork for an upper 15 inch layer. The weight of the dome is carried in axial compression along the hoops and meridians of the dome. The first finite element model uses shell elements and considers two limiting load cases; where the two layers act as one, and where the lower layer carries the weight of both. The openings interrupt the hoops and meridians and the weight of the dome must be redistributed around the openings. Without openings, the stresses due to dead load in the structure are very low when compared to the material strength. The impact of the openings is increased compression stresses near the opening. The maximum stresses are approximately four times larger than in the original structure. These results are confirmed by the second model which is made from layers of solid elements. This model shows a significant difference between the compression on the top surface of the dome, in the affected areas, and that on the bottom surface, leading to shear stresses. These shear stresses are largest around the

  15. Stability of Complex Biomolecular Structures: Vander Waals, Hydrogen Bond Cooperativity, and Nuclear Quantum Effects

    CERN Document Server

    Rossi, Mariana; Michaelides, Angelos

    2016-01-01

    Biomolecules are complex systems stabilized by a delicate balance of weak interactions, making it important to assess all energetic contributions in an accurate manner. However, it is a priori unclear which contributions make more of an impact. Here, we examine stacked polyglutamine (polyQ) strands, a peptide repeat often found in amyloid aggregates. We investigate the role of hydrogen bond (HB) cooperativity, van der Waals (vdW) dispersion interactions, and quantum contributions to free energies, including anharmonicities through density functional theory and ab initio path integral simulations. Of these various factors, we find that the largest impact on structural stabilization comes from vdW interactions. HB cooperativity is the second largest contribution as the size of the stacked chain grows. Competing nuclear quantum effects make the net quantum contribution small but very sensitive to anharmonicities, vdW, and the number of HBs. Our results suggest that a reliable treatment of these systems can only ...

  16. A sup 1 H nuclear magnetic resonance study of structural and organisational changes in the cell

    CERN Document Server

    Tunnah, S K

    2000-01-01

    Increasing importance is being placed on understanding the role of membrane lipids in many different areas of biochemistry. It is of interest to determine what interactions may occur between membrane lipids and drug species. Furthermore, an increasing body of evidence suggests that membrane lipids are involved in the pathology of numerous diseases such as rheumatoid arthritis, cancer and HIV. Clearly, the more information available on the mechanisms involved in diseases, the greater the potential for identifying a cure or even a prevention. sup 1 H nuclear magnetic resonance (NMR) spectroscopy was used to study the alterations in membrane lipid organisation and structure in intact, viable cultured cells. Changes in the sup 1 H NMR spectra and the spin-lattice relaxation measurements of the human K562 and the rat FRTL-5 cell lines were observed on the addition of the fatty acid species: triolein, evening primrose oil, arachidonic acid and ITF 1779. Results indicate that the membrane lipids are reorganised to a...

  17. Nuclear effects in F{sub 3} structure function of nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India)], E-mail: sajathar@rediffmail.com; Singh, S.K. [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Vacas, M.J. Vicente [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, 46100 Burjassot (Valencia) (Spain)

    2008-10-02

    We study nuclear effects in the F{sub 3}{sup A}(x) structure function in the deep inelastic neutrino reactions on iron by using a relativistic framework to describe the nucleon spectral functions in the nucleus. The results for the ratio R(x,Q{sup 2})=(F{sub 3}{sup A}(x,Q{sup 2}))/(AF{sub 3}{sup N}(x,Q{sup 2})) and the Gross-Llewellyn Smith (GLS) integral G(x,Q{sup 2})={integral}{sub x}{sup 1}dxF{sub 3}{sup A}(x,Q{sup 2}) in nuclei are discussed and compared with the recent results available in literature from theoretical and phenomenological analyses of experimental data.

  18. Systematic nuclear structure studies using relativistic mean field theory in mass region A ˜ 130

    Science.gov (United States)

    Shukla, A.; Åberg, Sven; Bajpeyi, Awanish

    2017-02-01

    Nuclear structure studies for even-even nuclei in the mass region \\backsim 130, have been performed, with a special focus around N or Z = 64. On the onset of deformation and lying between two closed shell, these nuclei have attracted attention in a number of studies. A revisit to these experimentally accessible nuclei has been made via the relativistic mean field. The role of pairing and density depletion in the interior has been specially investigated. Qualitative analysis between two versions of relativistic mean field suggests that there is no significant difference between the two approaches. Moreover, the role of the filling {{{s}}}1/2 orbital in density depletion towards the centre has been found to be consistent with our earlier work on the subject Shukla and Åberg (2014 Phys. Rev. C 89 014329).

  19. Proton nuclear Overhauser effect study of the heme active site structure of Coprinus macrorhizus peroxidase.

    Science.gov (United States)

    Dugad, L B; Goff, H M

    1992-07-13

    Proton nuclear Overhauser effect and paramagnetic relaxation measurements have been used to define more extensively the heme active site structure of Coprinus macrorhizus peroxidase, CMP (previously known as Coprinus cinereus peroxidase), as the ferric low-spin cyanide ligated complex. The results are compared with other well-characterized peroxidase enzymes. The NMR spectrum of CMPCN shows changes in the paramagnetically shifted resonances as a function of time, suggesting a significant heme disorder for CMP. The presence of proximal and distal histidine amino acid residues are common to the heme environments of both CMPCN and HRPCN. However, the upfield distal arginine signals of HRPCN are not evident in the 1H-NMR spectra of CMPCN.

  20. A study of thermal, structural and shielding safety analysis for dry storage of spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Shin, S. H. [Kyungpook Nationl Univ., Daegu (Korea, Republic of)

    1997-03-15

    As a replaced method for MRS, the dry storage has been intensively developed by the advanced countries of nuclear power technology. Currently, the domestic technology for the dry storage is also under development. In the present study, the developed technical standards for USNRC and its operation are summarized. Futhermore, the SAR for VECTRA's NUHOMES satisfied with DOE and NRC's requirements is inversely analyzed and combined with both USNRC's regulatory guide and LLNL's SARS. In the safety analysis of a dry storage, the principal design criteria which identifies the structural and mechanical safety criteria is investigated. Based on the design criteria, hypothetical accident analysis as well as off-normal operation analysis are investigated.

  1. Nuclear structure of proton-rich unstable nucleus 28P studied by g-factor measurement*

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yong-Nan; ZHOU Dong-Mei; K. Matsuta; M. Mihara; M. Fukuda; D. Nishimura; J. Komurasaki; D. Ishikawa; R. Matsumiya; T. Nagatomo; T. Izumikawa; S. Takahashi; H. Hirano; T. Ohtsubo; S. Momota; Y. Nojiri; A. Kitagawa; M. Kanazawa; M. Torikoshi; S. Sato; T. Minamisono; J.R. Alonso; G.F. Krebs; T. J. M. Symons; YUAN Da-Qing; ZUO Yi; FAN Ping; T. Suzuki; ZHANG Xi-Zhen; ZHU Sheng-Yun

    2009-01-01

    Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ =3+, T1/2=270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g=0.1028(27) is very much quenched from the Schmidt value,but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as 〈lp〉 = 0.43(29), 〈ln〉 = 1.85(29), 〈Sp〉 = 0.28(4), and 〈Sn〉 = 0.44(4).

  2. Nuclear Structure and Reaction Properties of Ne, Mg and Si Isotopes with RMF Densities

    CERN Document Server

    Panda, R N; Patra, S K

    2013-01-01

    We have studied nuclear structure and reaction properties of Ne, Mg and Si isotopes, using relativistic mean field densities, in the frame work of Glauber model. Total reaction cross section $\\sigma_R$ for Ne isotopes on 12C target have been calculated at incident energy 240 MeV. The results are compared with the experimental data and with the recent theoretical study [W. Horiuchi et al., Phys. Rev. C, 86, 024614 (2012)]. Study of $\\sigma_R$ using deformed densities have shown a good agreement with the data. We have also predicted total reaction cross section $\\sigma_R$ for Ne, Mg and Si isotopes as projectiles and 12C as target at different incident energies.

  3. Nuclear structure corrections for μ4He+ and μ3He+ spectroscopy

    Science.gov (United States)

    Nevo Dinur, Nir; Ji, Chen; Hernandez, Oscar; Bacca, Sonia; Barnea, Nir

    2016-09-01

    The proton charge radius was recently determined from muonic hydrogen spectroscopy with tenfold improved precision but 7 . 9 σ disagreement with the accepted value, leading to the ``proton radius puzzle''. To further investigate, and to obtain precise radii, these measurements were repeated in μ4He+ and μ3He+. This may also shed light on the discrepancy between isotope-shift measurements of the 4He -3He radius difference. However, the precision of radii determined from the muonic experiments is limited by the uncertainties in the nuclear structure corrections. We present first ab-initio calculations of these corrections that reduced the uncertainties from 20 % to the few percent goal. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. This work was supported in parts by the Natural Sciences and Engineering Research Council (Grant Number SAPIN-2015-00031).

  4. Challenges to self-acceleration in modified gravity from gravitational waves and large-scale structure

    Directory of Open Access Journals (Sweden)

    Lucas Lombriser

    2017-02-01

    Full Text Available With the advent of gravitational-wave astronomy marked by the aLIGO GW150914 and GW151226 observations, a measurement of the cosmological speed of gravity will likely soon be realised. We show that a confirmation of equality to the speed of light as indicated by indirect Galactic observations will have important consequences for a very large class of alternative explanations of the late-time accelerated expansion of our Universe. It will break the dark degeneracy of self-accelerated Horndeski scalar–tensor theories in the large-scale structure that currently limits a rigorous discrimination between acceleration from modified gravity and from a cosmological constant or dark energy. Signatures of a self-acceleration must then manifest in the linear, unscreened cosmological structure. We describe the minimal modification required for self-acceleration with standard gravitational-wave speed and show that its maximum likelihood yields a 3σ poorer fit to cosmological observations compared to a cosmological constant. Hence, equality between the speeds challenges the concept of cosmic acceleration from a genuine scalar–tensor modification of gravity.

  5. The Challenge of the Largest Structures in the Universe to Cosmology

    CERN Document Server

    Park, Changbom; Kim, Juhan; Gott, J Richard; Kim, Sungsoo S; Kim, Kap-Sung

    2012-01-01

    Large galaxy redshift surveys have long been used to constrain cosmological models and structure formation scenarios. In particular, the largest structures discovered observationally are thought to carry critical information on the amplitude of large-scale density fluctuations or homogeneity of the universe, and have often challenged the standard cosmological framework. The Sloan Great Wall (SGW) recently found in the Sloan Digital Sky Survey (SDSS) region casts doubt on the concordance cosmological model with a cosmological constant (i.e. the flat LCDM model). Here we show that the existence of the SGW is perfectly consistent with the LCDM model, a result that only our very large cosmological N-body simulation (the Horizon Run 2, HR2) could supply. In addition, we report on the discovery of a void complex in the SDSS much larger than the SGW, and show that such size of the largest void is also predicted in the LCDM paradigm. Our results demonstrate that an initially homogeneous isotropic universe with primor...

  6. Challenges to self-acceleration in modified gravity from gravitational waves and large-scale structure

    Science.gov (United States)

    Lombriser, Lucas; Lima, Nelson A.

    2017-02-01

    With the advent of gravitational-wave astronomy marked by the aLIGO GW150914 and GW151226 observations, a measurement of the cosmological speed of gravity will likely soon be realised. We show that a confirmation of equality to the speed of light as indicated by indirect Galactic observations will have important consequences for a very large class of alternative explanations of the late-time accelerated expansion of our Universe. It will break the dark degeneracy of self-accelerated Horndeski scalar-tensor theories in the large-scale structure that currently limits a rigorous discrimination between acceleration from modified gravity and from a cosmological constant or dark energy. Signatures of a self-acceleration must then manifest in the linear, unscreened cosmological structure. We describe the minimal modification required for self-acceleration with standard gravitational-wave speed and show that its maximum likelihood yields a 3σ poorer fit to cosmological observations compared to a cosmological constant. Hence, equality between the speeds challenges the concept of cosmic acceleration from a genuine scalar-tensor modification of gravity.

  7. Innovation and knowledge generation in cooperation nets: challenges for regulations in the nuclear safety area in Brazil; Inovacao e geracao de conhecimento nas redes de cooperacao: desafios para a regulacao na area de seguranca nuclear no Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Staude, Fabio

    2014-07-01

    The importance of inter-organisational cooperation within the innovation process has been increasingly recognized. In fact, all organisations, at some point, need to look to external sources for inputs to the process of building up technological competence. In this sense, through a detailed case study, this thesis examine theoretical and empirically how collaborative initiatives have supported the Brazilian nuclear regulatory body in the development and implementation of innovations, in order to verify the positive relationship between the collaboration and the organisational innovation performance. Emphasizing the importance of both internal sources of knowledge and external participation, the study encompasses documentary analysis, a preliminary survey and semi-structured interviews with the regulatory body employers in charge of controlling medical and research facilities and activities involving radiation sources. The thesis demonstrates that innovations developed and implemented in the Brazilian nuclear safety and security area are associated with collaborative initiatives, in order to improve the organizational capability to fulfill safety obligations, providing some important implications for regulatory body managers concerned with the management of innovation. The findings also identified actors with a significant degree of influence in the innovation process. The result reveals that the support provided by these actors has a significant influence on the innovation performance of the Brazilian nuclear regulatory body, suggesting that Brazil should adopt more interactive models of innovation and knowledge transfer. In addition, the findings show that these key actors can play a very distinctive role in the context of sectoral systems of innovation information regime. (author)

  8. Input/Output of ab-initio nuclear structure calculations for improved performance and portability

    Energy Technology Data Exchange (ETDEWEB)

    Laghave, Nikhil [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Many modern scientific applications rely on highly computation intensive calculations. However, most applications do not concentrate as much on the role that input/output operations can play for improved performance and portability. Parallelizing input/output operations of large files can significantly improve the performance of parallel applications where sequential I/O is a bottleneck. A proper choice of I/O library also offers a scope for making input/output operations portable across different architectures. Thus, use of parallel I/O libraries for organizing I/O of large data files offers great scope in improving performance and portability of applications. In particular, sequential I/O has been identified as a bottleneck for the highly scalable MFDn (Many Fermion Dynamics for nuclear structure) code performing ab-initio nuclear structure calculations. We develop interfaces and parallel I/O procedures to use a well-known parallel I/O library in MFDn. As a result, we gain efficient I/O of large datasets along with their portability and ease of use in the down-stream processing. Even situations where the amount of data to be written is not huge, proper use of input/output operations can boost the performance of scientific applications. Application checkpointing offers enormous performance improvement and flexibility by doing a negligible amount of I/O to disk. Checkpointing saves and resumes application state in such a manner that in most cases the application is unaware that there has been an interruption to its execution. This helps in saving large amount of work that has been previously done and continue application execution. This small amount of I/O provides substantial time saving by offering restart/resume capability to applications. The need for checkpointing in optimization code NEWUOA has been identified and checkpoint/restart capability has been implemented in NEWUOA by using simple file I/O.

  9. Structured information analysis for human reliability analysis of emergency tasks in nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Won Dea; Kim, Jae Whan; Park, Jin Kyun; Ha, Jae Joo [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-02-01

    More than twenty HRA (Human Reliability Analysis) methodologies have been developed and used for the safety analysis in nuclear field during the past two decades. However, no methodology appears to have universally been accepted, as various limitations have been raised for more widely used ones. One of the most important limitations of conventional HRA is insufficient analysis of the task structure and problem space. To resolve this problem, we suggest SIA (Structured Information Analysis) for HRA. The proposed SIA consists of three parts. The first part is the scenario analysis that investigates the contextual information related to the given task on the basis of selected scenarios. The second is the goals-means analysis to define the relations between the cognitive goal and task steps. The third is the cognitive function analysis module that identifies the cognitive patterns and information flows involved in the task. Through the three-part analysis, systematic investigation is made possible from the macroscopic information on the tasks to the microscopic information on the specific cognitive processes. It is expected that analysts can attain a structured set of information that helps to predict the types and possibility of human error in the given task. 48 refs., 12 figs., 11 tabs. (Author)

  10. Database structure and file layout of Nuclear Power Plant Database. Database for design information on Light Water Reactors in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Izumi, Fumio

    1995-12-01

    The Nuclear Power Plant Database (PPD) has been developed at the Japan Atomic Energy Research Institute (JAERI) to provide plant design information on domestic Light Water Reactors (LWRs) to be used for nuclear safety research and so forth. This database can run on the main frame computer in the JAERI Tokai Establishment. The PPD contains the information on the plant design concepts, the numbers, capacities, materials, structures and types of equipment and components, etc, based on the safety analysis reports of the domestic LWRs. This report describes the details of the PPD focusing on the database structure and layout of data files so that the users can utilize it efficiently. (author).

  11. Luneburg-lens-like universal structural Pauli attraction in nucleus-nucleus interactions: origin of emergence of cluster structures and nuclear rainbows

    CERN Document Server

    Ohkubo, Shigeo

    2016-01-01

    The Pauli exclusion principle plays an important role in many-body fermion systems preventing them from collapsing by repulsion. For example, the Pauli principle causes a repulsive potential at short distances between two $\\alpha$ particles. On the other hand, the existence of nuclear rainbows demonstrates that the inter-nuclear potential is sufficiently attractive in the internal region to cause refraction. The two concepts of repulsion and attraction are seemingly irreconcilable. Contrary to traditional understanding, it is shown that the Pauli principle causes a {\\it universal structural Pauli attraction} between nuclei rather than a {\\it structural repulsive core}. Through systematic studies of $\\alpha$+$\\alpha$, $\\alpha$+$^{16}$O, $\\alpha$+$^{40}$Ca and $^{16}$O+$^{16}$O systems, it is shown that the emergence of cluster structures near the threshold energy at low energies and nuclear rainbows at high energies is a direct consequence of the Pauli principle.

  12. Impact of oceanic submesoscale coherent structures on marine top predators: new tools and challenges

    Science.gov (United States)

    Tew-Kai, E.; Sudre, J.; Gremillet, D.; Yahia, H.; Rossi, V.; Hernandez-Garcia, E.; López, C.; Marsac, F.; Weimerskirch, H.; Garçon, V.

    2011-12-01

    In recent years it appears that meso- and submesoscale features (fronts, eddies, filaments) in surface ocean flow have a crucial influence on marine ecosystems. Their dynamics partly control the foraging behaviour and the movements of marine top. One of the challenges in ecology is to define critical habitats and understand the rules of habitat selection. Recently new tools for detection of coherent structures at submesoscale open the way for new studies never investigated before in marine ecology. Through two examples we highlight novel research on the importance of submesoscale structures for the spatial distribution of marine top predators. We studied two seabird populations with contrasting characteristics: Frigatebirds in the Mozambique Channel, and Cape gannets in the Benguela upwelling off southern Africa. Frigatebirds are mainly offshore birds while Cape gannets do not venture beyond the continental shelf. For these two studies, we used products derived from remote sensing data, to describe submesoscale coherent structures (Mozambique Channel resulting from an intense mesoscale activity. By comparing seabird satellite positions with LCSs locations, we demonstrate that frigatebirds track precisely these structures in the Mozambique Channel, providing the first evidence that a top predator is able to track these FSLE ridges to locate food patches. Although many questions remain unanswered, this work remains a pioneering on this topic. Despite the interest of FSLE, they are limited to offshore areas due to altimetry products limitation on continental shelves. However, many seabirds operate in coastal areas undergoing stronger anthropogenic pressures, such as Cape gannets off South Africa. The Benguela system is characterized by an upwelling inhabited by numerous fronts and filaments that very likely have a strong impact on seabird spatial distribution, and it was not possible to implement FSLE in this area. Thus, we used a newly developed method based on the

  13. Effects of reinforcement ratio and arrangement on the structural behavior of a nuclear building under aircraft impact

    Energy Technology Data Exchange (ETDEWEB)

    Thai, Duc-Kien; Kim, Seung-Eock, E-mail: sekim@sejong.ac.kr; Lee, Hyuk-Kee

    2014-09-15

    Highlights: • Numerical analysis of RC nuclear building model under aircraft impact was conducted. • The analysis result shows similar behavior as compared to the Riera function. • The effects of reinforcement ratio and arrangement were enumerated. • The appropriate number of layer of longitudinal rebar was recommended. - Abstract: This study presents the effectiveness of the rebar ratio and the arrangement of reinforced concrete (RC) structures on the structural behavior of nuclear buildings under aircraft impact using a finite element (FE) approach. A simplified model of a fictitious nuclear building using RC structures was fully modeled. The aircraft model of a Boeing 767-400 was used for impact simulation and was developed and verified with a conventional impact force–time history curve. The IRIS Punching test was used to validate the damage prediction capabilities of the RC wall under impact loading. With regard to the different rebar ratios and rebar arrangements of a nuclear RC building, the structural behavior of a building under aircraft impact was investigated. The structural behavior investigated included plastic deformation, displacement, energy dissipation, perforation/penetration depth and scabbing area. The results showed that the rebar ratio has a significant effect on withstanding aircraft impact and reducing local damage. With four layers of rebar, the RC wall absorbed and dissipated the impact energy more than once with only two layers of rebar for the same rebar ratio.

  14. Nuclear magnetic resonance structure and dynamics of the response regulator Sma0114 from Sinorhizobium meliloti.

    Science.gov (United States)

    Sheftic, Sarah R; Garcia, Preston P; White, Emma; Robinson, Victoria L; Gage, Daniel J; Alexandrescu, Andrei T

    2012-09-04

    Receiver domains control intracellular responses triggered by signal transduction in bacterial two-component systems. Here, we report the solution nuclear magnetic resonance structure and dynamics of Sma0114 from the bacterium Sinorhizobium meliloti, the first such characterization of a receiver domain from the HWE-kinase family of two-component systems. The structure of Sma0114 adopts a prototypical α(5)/β(5) Rossman fold but has features that set it apart from other receiver domains. The fourth β-strand of Sma0114 houses a PFxFATGY sequence motif, common to many HWE-kinase-associated receiver domains. This sequence motif in Sma0114 may substitute for the conserved Y-T coupling mechanism, which propagates conformational transitions in the 455 (α4-β5-α5) faces of receiver domains, to prime them for binding downstream effectors once they become activated by phosphorylation. In addition, the fourth α-helix of the consensus 455 face in Sma0114 is replaced with a segment that shows high flexibility on the pico- to nanosecond time scale by (15)N relaxation data. Secondary structure prediction analysis suggests that the absence of helix α4 may be a conserved property of the HWE-kinase-associated family of receiver domains to which Sma0114 belongs. In spite of these differences, Sma0114 has a conserved active site, binds divalent metal ions such as Mg(2+) and Ca(2+) that are required for phosphorylation, and exhibits micro- to millisecond active-site dynamics similar to those of other receiver domains. Taken together, our results suggest that Sma0114 has a conserved active site but differs from typical receiver domains in the structure of the 455 face that is used to effect signal transduction following activation.

  15. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

    Science.gov (United States)

    Singh, Gurpreet; Mohanty, B P; Saini, G S S

    2016-02-15

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  16. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques

    Science.gov (United States)

    Singh, Gurpreet; Mohanty, B. P.; Saini, G. S. S.

    2016-02-01

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  17. Structural Characteristics and Mechanical Properties of Rock Mass in the Field of Tianwan Nuclear Power Plant, China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The structural characteristics and mechanical properties of the rock mass are important parts of the feasibility study on the nuclear power engineering field. In this study, by means of in situ investigation and statistics,the structural plane and joint fissure features of the rock mass were analyzed and discussed at different plots and different depth scopes in the Tianwan Nuclear Power engineering field, the rock mass integrality and its weathered degree were evaluated respectively, and especially, the unfavorable geological phenomena of strongly-weathered cystid existing in the field were studied. According to the results of indoor rock mechanical tests, in combination with drilling, the shallow seismic prospecting, sonic logging and point load tests, the statistical results of physical and mechanical indices of rocks at key plots of the field were analyzed, and the design parameters of the field were calculated. It provided scientific basis for the foundation design of the nuclear power plant.

  18. Structural and mechanical characterization of ion-irradiated glassy polymeric carbon for TRISO fuel nuclear application

    Science.gov (United States)

    Abunaemeh, Malek; Seif, Mohamed; Elsamadicy, Abdalla; Ila, Daryush

    2012-08-01

    Tristructural isotropic (TRISO) fuel is considered as the fuel design of choice for the next generation of nuclear reactors (Generation IV). Its design consists of a fuel kernel of UO x coated with several layers having different functions. One of these functions is a containment shell/diffusion barrier for the fission fragments. Normally, the material of choice for this shell is pyrolytic carbon (PyC). The material does not offer a perfect barrier, due to its inherent crystalline structure, which is planar (like graphite) and therefore impossible to mold in one continuous sheet around the spherical fuel bead. Plane boundaries allow fragment diffusion at a much higher rate than through the plane. In this study, we investigate the possibility of replacing PyC with a different form of carbon, glassy polymeric carbon (GPC). We prepared samples of GPC and studied the evolution of their physical properties and structure as a function of the radiation environment that they were exposed to. The temperature at which the samples were held during irradiation was very similar to the Generation IV nuclear reactor (∼1000°C). During the fission of U235, the fission fragment mass distribution has two maxima around 98 and 137 amu, which would best correspond to elements Rb and Cs, respectively. However, both ions are hard to produce from our SNICS ion source at the Center for Irradiation of Materials; therefore, we used 107Ag and 197Au as best replacements. The irradiation sessions consisted in various fluences of 5 MeV Ag, and 5 MeV Au. For elemental sample analysis, we used transmission electron microscopy. For mechanical analysis, we used nano-indentation. It is of prime importance to measure the penetration of the implanted 107Ag.and 197Au and the evolution of mechanical properties of GPC irradiated with these ions. A procedure for manufacturing GPC with analysis is presented. This will show how the GPC structure differs as the temperature that it is prepared at increases

  19. Two lanthanide-hydroxo clusters with different nuclearity: Synthesis, structures, luminescent and magnetic properties

    Science.gov (United States)

    Li, Xi-Li; Zhu, Cancan; Zhang, Xue-Li; Hu, Ming; Wang, Ai-Ling; Xiao, Hong-Ping

    2017-01-01

    Under the identical reaction conditions, two new TbIII and SmIII-hydroxo clusters with different nuclearity have been prepared and characterized by X-ray crystallography, spectroscopic methods and magnetic measurements. Solid-state structure analyses reveal that the TbIII cluster shows a pentanuclear square pyramidal shape of the composition [Tb5(μ3-OH)4(μ4-OH)(dbm)10]·2H2O (1, dbm- = dibenzoylmethanate) with the dbm ligands presenting two types of coordination modes [η2-and (μ-O)-η2-]. The SmIII species presents a tetranuclear parallelogram structure formulated as [Sm4(μ3-OH)2(dbm)10]·12H2O (2), and three types of coordination modes [η2-, (μ-O)-η2- and (μ-O)2-η2-] for dbm ligands are observed. The measurements of magnetic properties indicate that the direct-current (dc) magnetic behaviors of two clusters mainly result from the thermal depopulation of the Stark sublevels of the TbIII and SmIII ions, respectively. Meanwhile, alternating current (ac) magnetic susceptibility of 1 is also assessed. Investigations on luminescence properties show that 2 displays characteristic emission of the SmIII ion in visible range, while 1 does not exhibit any detectable emission. The interpretations of different emission behaviors for 1 and 2 are also presented in detail.

  20. Adenovirus replication is coupled with the dynamic properties of the PML nuclear structure.

    Science.gov (United States)

    Doucas, V; Ishov, A M; Romo, A; Juguilon, H; Weitzman, M D; Evans, R M; Maul, G G

    1996-01-15

    Wild-type PML and at least four other novel proteins are localized within discrete nuclear structures known as PODs. We demonstrate here that during adenovirus infection, immediate early viral proteins from the E1 and E4 transcription units associate with the POD, which in turn undergoes a dramatic morphological change. During this process, the auto-antigen Sp-100 and NDP55 but not PML, relocate from the POD to the viral inclusion bodies, the sites of adenovirus DNA replication and late RNA transcription. The E4-ORF3 11-kD protein alone will induce this reorganization and reciprocally, viruses carrying mutations in the E4-domain fail to do so. These same viral mutants are defective in viral replication as well as the accumulation of late viral mRNAs and host cell transcription shutoff. We show that interferon (INF) treatment enhances the expression of PML, reduces or blocks PODs reorganization, and inhibits BrdU incorporation into viral inclusion bodies. In addition, cell lines engineered to overexpress PML prevent PODs from viral-induced reorganization and block or severely delay adenovirus replication. These results suggest that viral replication relies on components of the POD and that the structure is a target of early viral proteins.

  1. Non-observable nature of the nuclear shell structure. Meaning, illustrations and consequences

    CERN Document Server

    Duguet, T; Holt, J D; Somà, V

    2014-01-01

    The concept of single-nucleon shells constitutes a basic pillar of our understanding of nuclear structure. Effective single-particle energies (ESPEs) introduced by French and Baranger represent the most appropriate tool to relate many-body observables to a single-nucleon shell structure. As briefly discussed in [T. Duguet, G. Hagen, Phys. Rev. C {\\bf 85}, 034330 (2012)], the dependence of ESPEs on one-nucleon transfer probability matrices makes them purely theoretical quantities that "run" with the non-observable resolution scale $\\lambda$ employed in the calculation. Given that ESPEs provide a way to interpret the many-body problem in terms of simpler theoretical ingredients, the goal is to specify the terms, i.e. the exact sense and conditions, in which this interpretation can be conducted meaningfully. State-of-the-art multi-reference in-medium similarity renormalization group and self-consistent Gorkov Green's function many-body calculations are employed to corroborate the formal analysis. This is done by...

  2. Structural Safety Analysis Based on Seismic Service Conditions for Butterfly Valves in a Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Sang-Uk Han

    2014-01-01

    Full Text Available The structural integrity of valves that are used to control cooling waters in the primary coolant loop that prevents boiling within the reactor in a nuclear power plant must be capable of withstanding earthquakes or other dangerous situations. In this study, numerical analyses using a finite element method, that is, static and dynamic analyses according to the rigid or flexible characteristics of the dynamic properties of a 200A butterfly valve, were performed according to the KEPIC MFA. An experimental vibration test was also carried out in order to verify the results from the modal analysis, in which a validated finite element model was obtained via a model-updating method that considers changes in the in situ experimental data. By using a validated finite element model, the equivalent static load under SSE conditions stipulated by the KEPIC MFA gave a stress of 135 MPa that occurred at the connections of the stem and body. A larger stress of 183 MPa was induced when we used a CQC method with a design response spectrum that uses 2% damping ratio. These values were lower than the allowable strength of the materials used for manufacturing the butterfly valve, and, therefore, its structural safety met the KEPIC MFA requirements.

  3. Structural safety analysis based on seismic service conditions for butterfly valves in a nuclear power plant.

    Science.gov (United States)

    Han, Sang-Uk; Ahn, Dae-Gyun; Lee, Myeong-Gon; Lee, Kwon-Hee; Han, Seung-Ho

    2014-01-01

    The structural integrity of valves that are used to control cooling waters in the primary coolant loop that prevents boiling within the reactor in a nuclear power plant must be capable of withstanding earthquakes or other dangerous situations. In this study, numerical analyses using a finite element method, that is, static and dynamic analyses according to the rigid or flexible characteristics of the dynamic properties of a 200A butterfly valve, were performed according to the KEPIC MFA. An experimental vibration test was also carried out in order to verify the results from the modal analysis, in which a validated finite element model was obtained via a model-updating method that considers changes in the in situ experimental data. By using a validated finite element model, the equivalent static load under SSE conditions stipulated by the KEPIC MFA gave a stress of 135 MPa that occurred at the connections of the stem and body. A larger stress of 183 MPa was induced when we used a CQC method with a design response spectrum that uses 2% damping ratio. These values were lower than the allowable strength of the materials used for manufacturing the butterfly valve, and, therefore, its structural safety met the KEPIC MFA requirements.

  4. Ultrasonic Fingerprinting of Structural Materials: Spent Nuclear Fuel Containers Case-Study

    Science.gov (United States)

    Sednev, D.; Lider, A.; Demyanuk, D.; Kroening, M.; Salchak, Y.

    Nowadays, NDT is mainly focused on safety purposes, but it seems possible to apply those methods to provide national and IAEA safeguards. The containment of spent fuel in storage casks could be dramatically improved in case of development of so-called "smart" spent fuel storage and transfer casks. Such casks would have tamper indicating and monitoring/tracking features integrated directly into the cask design. The microstructure of the containers material as well as of the dedicated weld seam is applied to the lid and the cask body and provides a unique fingerprint of the full container, which can be reproducibly scanned by using an appropriate technique. The echo-sounder technique, which is the most commonly used method for material inspection, was chosen for this project. The main measuring parameter is acoustic noise, reflected from material's artefacts. The purpose is to obtain structural fingerprinting. Reference measurement and additional measurement results were compared. Obtained results have verified the appliance of structural fingerprint and the chosen control method. The successful authentication demonstrates the levels of the feature points' compliance exceeding the given threshold which differs considerably from the percentage of the concurrent points during authentication from other points. Since reproduction or doubling of the proposed unique identification characteristics is impossible at the current state science and technology, application of this technique is considered to identify the interference into the nuclear materials displacement with high accuracy.

  5. Investigating the effects of stress on the pore structures of nuclear grade graphites

    Science.gov (United States)

    Taylor, Joshua E. L.; Hall, Graham N.; Mummery, Paul M.

    2016-03-01

    Graphite is used as a moderating material and as a structural component in a number of current generation nuclear reactors. During reactor operation stresses develop in the graphite components, causing them to deform. It is important to understand how the microstructure of graphite affects the material's response to these stresses. A series of experiments were performed to investigate how the pore structures of Pile Grade A and Gilsocarbon graphites respond to loading stresses. A compression rig was used to simulate the build-up of operational stresses in graphite components, and a confocal laser microscope was used to study variation of a number of important pore properties. Values of elastic modulus and Poisson's ratio were calculated and compared to existing literature to confirm the validity of the experimental techniques. Mean pore areas were observed to decrease linearly with increasing applied load, mean pore eccentricity increased linearly, and a small amount of clockwise pore rotation was observed. The response to build-up of stresses was dependent on the orientation of the pores and basal planes and the shapes of the pores with respect to the loading axis. It was proposed that pore closure and pore reorientation were competing processes. Pore separation was quantified using 'nearest neighbour' and Voronoi techniques, and non-pore regions were found to shrink linearly with increasing applied load.

  6. Sternheimer free determination of the 51V nuclear quadrupole moment from hyperfine structure measurements

    Science.gov (United States)

    Unkel, P.; Buch, P.; Dembczyński, J.; Ertmer, W.; Johann, U.

    1989-12-01

    The hyperfine structure (hfs) of 18 metastable states of51V has been measured by laser induced fluorescence. 15 of these states have been measured additionally very precisely by the ABMR-LIRF method. Using results of earlier hfs measurements, the hfs of altogether 33 fine structure states is analyzed using a method of simultaneous parametrization of one- and two-body interactions in the atomic hfs of the model space 3 d 3 + M 4 s 2 - M ( M = 0, 1, 2). The hfs of these states is described by 16 parameters for the magnetic dipole interaction and 12 parameters for the electric quadrupole interaction. From these model space parameters corresponding configuration dependent parameters for the three configurations were determined. These parameters allow a prediction of the hfs constants of all states of the modelspace within an accuracy of 5 to 10%. The evaluation of the nuclear quadrupole moment of51V, free of Sternheimer corrections up to second order, yielded the value of -0.043(5) barn.

  7. Lithography-based ceramic manufacture (LCM) of auxetic structures: present capabilities and challenges

    Science.gov (United States)

    Díaz Lantada, Andrés; de Blas Romero, Adrián; Schwentenwein, Martin; Jellinek, Christopher; Homa, Johannes

    2016-05-01

    Auxetic metamaterials are known for having a negative Poisson’s ratio (NPR) and for displaying the unexpected properties of lateral expansion when stretched and densification when compressed. Even though a wide set of micro-manufacturing resources have been used for the development of auxetic metamaterials and related devices, additional precision and an extension to other families of materials is needed for their industrial expansion. In addition, their manufacture using ceramic materials is still challenging. In this study we present a very promising approach for the development of auxetic metamaterials and devices based on the use of lithography-based ceramic manufacturing. The process stands out for its precision and complex three-dimensional geometries attainable, without the need of supporting structures, and for enabling the manufacture of ceramic auxetics with their geometry controlled from the design stage with micrometric precision. To our knowledge it represents the first example of application of this technology to the manufacture of auxetic geometries using ceramic materials. We have used a special three-dimensional auxetic design whose remarkable NPR has been previously highlighted.

  8. A Study on the Dynamic Analysis of the Nuclear Fuel Test Rig Using 1-Way Fluid-Structure Coupled Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tae-Ho; Hong, Jin-Tae; Ahn, Sung-Ho; Joung, Chang-Young; Heo, Sung-Ho; Jang, Seo-Yun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    1-way fluid-structure coupled analysis is used to estimate the dynamic characteristic of the fuel test rig. the motion at the bottom of the test rig is confirmed. The maximum deformation of the test rig is 0.11 mm. The structural integrity of the test rig is performed by using the comparison with the Von-mises stress of the analysis and yield stress of the material. It is evaluated that the motion at the bottom of the test rig is able to cause other structural problem. Using the 2-way fluid-structural coupled analysis, the structural integrity of the test rig will be performed in further paper. The cooling water with specific flow rate was flowed in the nuclear fuel test rig. The structural integrity of the test rig was affected by the vibration. The fluid-induced vibration test had to be performed to obtain the amplitude of the vibration on the structure. Various test systems was developed. Flow-induced vibration and pressure drop experimental tester was developed in Korea Atomic Energy Research Institute. The vibration test with high fluid flow rate was difficult by the tester. To generate the nuclear fuel test environment, coolant flow simulation system was developed. The scaled nuclear fuel test was able to be performed by the simulation system. The mock-up model of the test rig was used in the simulation system. The mock-up model in the simulation system was manufactured with scaled down full model. In this paper, the fluid induced vibration characteristic of the full model in the nuclear fuel test is studied. The hydraulic pressure on the velocity of the fluid was calculated. The static structure analysis was performed by using the pressure. The structural integrity was assessed using the results of the analysis.

  9. Track structure based modelling of light ion radiation effects on nuclear and mitochondrial DNA

    Science.gov (United States)

    Schmitt, Elke; Ottolenghi, Andrea; Dingfelder, Michael; Friedland, Werner; Kundrat, Pavel; Baiocco, Giorgio

    2016-07-01

    Space radiation risk assessment is of great importance for manned spaceflights in order to estimate risks and to develop counter-measures to reduce them. Biophysical simulations with PARTRAC can help greatly to improve the understanding of initial biological response to ionizing radiation. Results from modelling radiation quality dependent DNA damage and repair mechanisms up to chromosomal aberrations (e.g. dicentrics) can be used to predict radiation effects depending on the kind of mixed radiation field exposure. Especially dicentric yields can serve as a biomarker for an increased risk due to radiation and hence as an indicator for the effectiveness of the used shielding. PARTRAC [1] is a multi-scale biophysical research MC code for track structure based initial DNA damage and damage response modelling. It integrates physics, radiochemistry, detailed nuclear DNA structure and molecular biology of DNA repair by NHEJ-pathway to assess radiation effects on cellular level [2]. Ongoing experiments with quasi-homogeneously distributed compared to sub-micrometre focused bunches of protons, lithium and carbon ions allow a separation of effects due to DNA damage complexity on nanometre scale from damage clustering on (sub-) micrometre scale [3, 4]. These data provide an unprecedented benchmark for the DNA damage response model in PARTRAC and help understand the mechanisms leading to cell killing and chromosomal aberrations (e.g. dicentrics) induction. A large part of space radiation is due to a mixed ion field of high energy protons and few heavier ions that can be only partly absorbed by the shielding. Radiation damage induced by low-energy ions significantly contributes to the high relative biological efficiency (RBE) of ion beams around Bragg peak regions. For slow light ions the physical cross section data basis in PARTRAC has been extended to investigate radiation quality effects in the Bragg peak region [5]. The resulting range and LET values agree with ICRU data

  10. Feasibility of nuclear ribosomal region ITS1 over ITS2 in barcoding taxonomically challenging genera of subtribe Cassiinae (Fabaceae)

    Science.gov (United States)

    Mishra, Priyanka; Kumar, Amit; Rodrigues, Vereena; Shukla, Ashutosh K.

    2016-01-01

    the similarity-based methods producing well-resolved phylogenetic trees with many nodes well supported by bootstrap analyses. Conclusion The reticulated phylogenetic hypothesis using the ITS1 region mainly supported the relationship between the species of Cassiinae established by traditional morphological methods. The ITS1 region showed a higher discrimination power and desirable characteristics as compared to ITS2 and ITS1 + 2, thereby concluding to be the locus of choice. Considering the complexity of the group and the underlying biological ambiguities, the results presented here are encouraging for developing DNA barcoding as a useful tool for resolving taxonomical challenges in corroboration with morphological framework. PMID:27994958

  11. Feasibility of nuclear ribosomal region ITS1 over ITS2 in barcoding taxonomically challenging genera of subtribe Cassiinae (Fabaceae

    Directory of Open Access Journals (Sweden)

    Priyanka Mishra

    2016-12-01

    outperformed the similarity-based methods producing well-resolved phylogenetic trees with many nodes well supported by bootstrap analyses. Conclusion The reticulated phylogenetic hypothesis using the ITS1 region mainly supported the relationship between the species of Cassiinae established by traditional morphological methods. The ITS1 region showed a higher discrimination power and desirable characteristics as compared to ITS2 and ITS1 + 2, thereby concluding to be the locus of choice. Considering the complexity of the group and the underlying biological ambiguities, the results presented here are encouraging for developing DNA barcoding as a useful tool for resolving taxonomical challenges in corroboration with morphological framework.

  12. Structure of the nuclear exosome component Rrp6p reveals an interplay between the active site and the HRDC domain

    DEFF Research Database (Denmark)

    Midtgaard, Søren Fuglsang; Assenholt, Jannie; Jonstrup, Anette Thyssen

    2006-01-01

    The multisubunit eukaryotic exosome is an essential RNA processing and degradation machine. In its nuclear form, the exosome associates with the auxiliary factor Rrp6p, which participates in both RNA processing and degradation reactions. The crystal structure of Saccharomyces cerevisiae Rrp6p...

  13. Study of nuclear structure effect on fusion through barrier distribution for the system 28Si+154Sm

    Directory of Open Access Journals (Sweden)

    Kaur Gurpreet

    2015-01-01

    Full Text Available We plan to perform large angle quasi-elastic scattering experiments using a 28Si beam on heavy targets in order to study the nuclear dynamics and structure effects. As a prelude to our first test experiment with a 154Sm target, we study here the existing fusion data for the same system through the barrier distribution.

  14. First-principles Electronic Structure Calculations for Scintillation Phosphor Nuclear Detector Materials

    Science.gov (United States)

    Canning, Andrew

    2013-03-01

    Inorganic scintillation phosphors (scintillators) are extensively employed as radiation detector materials in many fields of applied and fundamental research such as medical imaging, high energy physics, astrophysics, oil exploration and nuclear materials detection for homeland security and other applications. The ideal scintillator for gamma ray detection must have exceptional performance in terms of stopping power, luminosity, proportionality, speed, and cost. Recently, trivalent lanthanide dopants such as Ce and Eu have received greater attention for fast and bright scintillators as the optical 5d to 4f transition is relatively fast. However, crystal growth and production costs remain challenging for these new materials so there is still a need for new higher performing scintillators that meet the needs of the different application areas. First principles calculations can provide a useful insight into the chemical and electronic properties of such materials and hence can aid in the search for better new scintillators. In the past there has been little first-principles work done on scintillator materials in part because it means modeling f electrons in lanthanides as well as complex excited state and scattering processes. In this talk I will give an overview of the scintillation process and show how first-principles calculations can be applied to such systems to gain a better understanding of the physics involved. I will also present work on a high-throughput first principles approach to select new scintillator materials for fabrication as well as present more detailed calculations to study trapping process etc. that can limit their brightness. This work in collaboration with experimental groups has lead to the discovery of some new bright scintillators. Work supported by the U.S. Department of Homeland Security and carried out under U.S. Department of Energy Contract no. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory.

  15. Probability based load criteria for the design of nuclear structures: a critical review of the state-of-the-art

    Energy Technology Data Exchange (ETDEWEB)

    Shinozuka, M.; Ellingwood, B.R.; Wang, P.C.; Meyer, C.; Wen, Y.K.; Kao, S.; Shooman, M.L.; Philippacopoulos, A.J.

    1981-04-01

    Structures for nuclear power plant facilities must be designed to withstand safely and effectively all kinds of loads and load combinations that may be expected to occur during their lifetime. The traditional methods of structural design attempt to account for the inevitable variability in the loads, material strengths, in-service environments, and fabrication process, etc., through the use of safety factor, allowable stresses or load and resistance factors. These approaches may result in an unknown and nonuniform reliability because of the subjective manner in which the safety factors have been determined. The stochastic nature loads and the uncertainties in material properties dictate a probabilistic approach for a rational assessment of structural safety and performance. This report presents: an in-depth review of the state-of-the-art pertaining to probability-based analysis and design of civil engineering structures; basis for extending existing probability-based methods to seismic category I nuclear structures; and the availability of the pertinent data required to perform probabilistic analysis for seismic category I nuclear structures.

  16. Unified field theory from the classical wave equation: Preliminary application to atomic and nuclear structure

    Science.gov (United States)

    Múnera, Héctor A.

    2016-07-01

    It is postulated that there exists a fundamental energy-like fluid, which occupies the flat three-dimensional Euclidean space that contains our universe, and obeys the two basic laws of classical physics: conservation of linear momentum, and conservation of total energy; the fluid is described by the classical wave equation (CWE), which was Schrödinger's first candidate to develop his quantum theory. Novel solutions for the CWE discovered twenty years ago are nonharmonic, inherently quantized, and universal in the sense of scale invariance, thus leading to quantization at all scales of the universe, from galactic clusters to the sub-quark world, and yielding a unified Lorentz-invariant quantum theory ab initio. Quingal solutions are isomorphic under both neo-Galilean and Lorentz transformations, and exhibit nother remarkable property: intrinsic unstability for large values of ℓ (a quantum number), thus limiting the size of each system at a given scale. Unstability and scale-invariance together lead to nested structures observed in our solar system; unstability may explain the small number of rows in the chemical periodic table, and nuclear unstability of nuclides beyond lead and bismuth. Quingal functions lend mathematical basis for Boscovich's unified force (which is compatible with many pieces of evidence collected over the past century), and also yield a simple geometrical solution for the classical three-body problem, which is a useful model for electronic orbits in simple diatomic molecules. A testable prediction for the helicoidal-type force is suggested.

  17. Nuclear quantum effects in the structure and lineshapes of the N2 NEXAFS spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Fatehi, Shervin; Schwartz, Craig P.; Saykally, Richard J.; Prendergast, David

    2009-12-04

    We study the relative ability of several models of the X-ray absorption spectrum to capture the Franck-Condon structure apparent from an experiment on gaseous nitrogen. In doing so, we adopt the Born-Oppenheimer approximation and a constrained density functional theory method for computing the energies of the X-ray-excited molecule. Starting from an otherwise classical model for the spectrum, we systematically introduce more realistic physics, first by substituting the quantum mechanical nuclear radial density in the bond separation R for the classical radial density, then by adding the effect of zero-point energy and other level shifts, and finally by including explicit rovibrational quantization of both the ground and excited states. The quantization is determined exactly, using a discrete variable representation. We show that the NEXAFS spectrum can be predicted semiquantiatively within this framework. We also address the possibility of non-trivial temperature dependence in the spectrum. Finally, we show that it is possible to improve the predicted spectrum by using constrained DFT in combination with more accurate potentials.

  18. A nucleus-dependent valence-space approach to nuclear structure

    CERN Document Server

    Stroberg, S R; Hergert, H; Holt, J D; Bogner, S K; Roth, R; Schwenk, A

    2016-01-01

    We present a nucleus-dependent valence-space approach for calculating ground and excited states of nuclei, which generalizes the shell-model in-medium similarity renormalization group to an ensemble reference with fractionally filled orbitals. Because the ensemble is used only as a reference, and not to represent physical states, no symmetry restoration is required. This allows us to capture 3N forces among valence nucleons with a valence-space Hamiltonian specifically targeted to each nucleus of interest. Predicted ground-state energies from carbon through nickel agree with results of other large-space ab initio methods, generally to the 1\\% level. In addition, we show that this new approach is required in order to obtain convergence for nuclei in the upper $p$ and $sd$ shells. Finally, we address the $1^+$/$3^+$ ground-state inversion problem in $^{22}\\text{Na}$ and $^{46}\\text{V}$. This approach extends the reach of ab initio nuclear structure calculations to essentially all light- and medium-mass nuclei.

  19. Manufacturing Challenges Associated with the Use of Metal Matrix Composites in Aerospace Structures

    Science.gov (United States)

    Prater, Tracie

    2014-01-01

    Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramic particles or fibers. These materials possess a very high strength to weight ratio, good resistance to impact and wear, and a number of other properties which make them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as NASA's Orion Crew Exploration Vehicle and Space Launch System. A current focus of FSW research is to extend the process to new materials, such as MMCs, which are difficult to weld using conventional fusion techniques. Since Friction Stir Welding occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This chapter summarizes the challenges encountered when joining MMCs to themselves or to other materials in structures. Specific attention is paid to the influence of process variables in Friction Stir Welding on the wear process characterizes the effect of process parameters (spindle speed, traverse rate, and length

  20. Insight into structure and assembly of the nuclear pore complex by utilizing the genome of a eukaryotic thermophile

    DEFF Research Database (Denmark)

    Amlacher, Stefan; Sarges, Phillip; Flemming, Dirk;

    2011-01-01

    Despite decades of research, the structure and assembly of the nuclear pore complex (NPC), which is composed of ~30 nucleoporins (Nups), remain elusive. Here, we report the genome of the thermophilic fungus Chaetomium thermophilum (ct) and identify the complete repertoire of Nups therein. The the......Despite decades of research, the structure and assembly of the nuclear pore complex (NPC), which is composed of ~30 nucleoporins (Nups), remain elusive. Here, we report the genome of the thermophilic fungus Chaetomium thermophilum (ct) and identify the complete repertoire of Nups therein....... The thermophilic proteins show improved properties for structural and biochemical studies compared to their mesophilic counterparts, and purified ctNups enabled the reconstitution of the inner pore ring module that spans the width of the NPC from the anchoring membrane to the central transport channel. This module...... of a thermophilic eukaryote for studying complex molecular machines....