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Sample records for nonproliferation act ina

  1. 76 FR 818 - Bureau of Nonproliferation; Determination Under the Arms Export Control Act

    Science.gov (United States)

    2011-01-06

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Bureau of Nonproliferation; Determination Under the Arms Export Control Act AGENCY: Department of State... determination pursuant to Section 73 of the Arms Export Control Act and has concluded that publication of...

  2. Nuclear Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Atkins-Duffin, C E

    2008-12-10

    With an explosion equivalent of about 20kT of TNT, the Trinity test was the first demonstration of a nuclear weapon. Conducted on July 16, 1945 in Alamogordo, NM this site is now a Registered National Historic Landmark. The concept and applicability of nuclear power was demonstrated on December 20, 1951 with the Experimental Breeder Reactor Number One (EBR-1) lit four light bulbs. This reactor is now a Registered National Historic Landmark, located near Arco, ID. From that moment forward it had been clearly demonstrated that nuclear energy has both peaceful and military applications and that the civilian and military fuel cycles can overlap. For the more than fifty years since the Atoms for Peace program, a key objective of nuclear policy has been to enable the wider peaceful use of nuclear energy while preventing the spread of nuclear weapons. Volumes have been written on the impact of these two actions on the world by advocates and critics; pundits and practioners; politicians and technologists. The nations of the world have woven together a delicate balance of treaties, agreements, frameworks and handshakes that are representative of the timeframe in which they were constructed and how they have evolved in time. Collectively these vehicles attempt to keep political will, nuclear materials and technology in check. This paper captures only the briefest abstract of the more significant aspects on the Nonproliferation Regime. Of particular relevance to this discussion is the special nonproliferation sensitivity associated with the uranium isotope separation and spent fuel reprocessing aspects of the nuclear fuel cycle.

  3. Reevaluating the Process: An Assessment of the Iran Nonproliferation Act and its Impact on the International Space Station Program

    Science.gov (United States)

    2005-04-05

    concessions made to the INA. The next sacrifice was the fiscally sensible use of comparative advantage. Russian contractors, in particular Energia and...NASA primarily contracts with three Russian companies: Russia’s space agency Roscosmos; the rocket and space corporation Energia that builds the Soyuz

  4. World Nonproliferation Regime

    Institute of Scientific and Technical Information of China (English)

    Ouyang Liping; Wu Xingzuo

    2007-01-01

    2006 witnessed an intense struggle between nuclear proliferation and nonproliferation. Iran's nuclear issue and North Korea's nuclear test have cast a deep shadow over the current international nonproliferation regime. The international contest for civil nuclear development became especially fierce as global energy prices went up. Such a situation , to some extent, accelerated the pace of nuclear proliferation. Furthermore, the existing international nonproliferation regime, based upon the Nuclear Nonproliferation Treaty (NPT), was affected by loopholes, and the U.S. failed in its ambition to unite other forces to mend fences. The international community needs to come up with a comprehensive and long-term strategy to meet the demand for an effective future nonproliferation regime in a healthy nuclear order.

  5. 75 FR 11223 - Lifting of Nonproliferation Measures Against One Russian Entity

    Science.gov (United States)

    2010-03-10

    ... FR 42089). Dated: March 4, 2010. Vann H. Van Diepen, Acting Assistant Secretary of State for... of Nonproliferation Measures Against One Russian Entity AGENCY: Department of State. ACTION: Notice..., 1994, as amended, to remove nonproliferation measures on one Russian entity. DATES: Effective...

  6. 75 FR 5836 - Lifting of Nonproliferation Measures Against One Russian Entity

    Science.gov (United States)

    2010-02-04

    ... July 30, 1998 (see 63 FR 42089). Dated: January 29, 2010. C.S. Eliot Kang, Acting Assistant Secretary... of Nonproliferation Measures Against One Russian Entity AGENCY: Department of State. ACTION: Notice..., 1994, as amended, to remove nonproliferation measures on one Russian entity. DATES: Effective...

  7. 22 CFR 40.205 - Applicant for immigrant visa under INA 203(c).

    Science.gov (United States)

    2010-04-01

    ... NONIMMIGRANTS AND IMMIGRANTS UNDER THE IMMIGRATION AND NATIONALITY ACT, AS AMENDED Failure to Comply with INA... under INA 203(c) if the alien does not have a high school education or its equivalent, as defined in...

  8. Robust Indicators of Nonproliferation Performance

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, Mara R.; Kurzrok, Andrew J.

    2014-02-13

    Understanding how the nuclear industry may benefit from self-regulation is closely linked with understanding how to report compliance activities for nonproliferation and export control objectives, as well as how to distinguish high and low compliance performance. Drawing on the corporate sustainability reporting model, nuclear and dual-use commodities industries can frame socially responsible self-regulatory activities to distinguish themselves as good nonproliferators.

  9. Former Nonproliferation Graduate Fellow Served at U.S. Mission

    Energy Technology Data Exchange (ETDEWEB)

    Brim, Cornelia P.

    2014-10-01

    Because of her training and professional experiences, Rosalyn Leitch, a Security Specialist at Pacific Northwest National Laboratory and former Nonproliferation Graduate Fellow with NIS (2012-2013) was able to transition into temporary assignment as UNVIE Acting Nuclear Security Attaché from November 2013 through February 2014.

  10. Broadening Industry Governance to Include Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Hund, Gretchen; Seward, Amy M.

    2008-11-11

    As industry is the first line of defense in detecting and thwarting illicit trade networks, the engagement of the private sector is critical to any government effort to strengthen existing mechanisms to protect goods and services throughout the supply chain. This study builds on previous PNNL work to continue to evaluate means for greater industry engagement to complement and strengthen existing governmental efforts to detect and stem the trade of illicit goods and to protect and secure goods that could be used in making a weapon of mass destruction. Specifically, the study evaluates the concept of Industry Self Regulation, defined as a systematic voluntary program undertaken by an industry or by individual companies to anticipate, implement, supplement, or substitute for regulatory requirements in a given field, generally through the adoption of best practices. Through a series of interviews with companies with a past history of non-compliance, trade associations and NGOs, the authors identify gaps in the existing regulatory infrastructure, drivers for a self regulation approach and the form such an approach might take, as well as obstacles to be overcome. The authors conclude that it is at the intersection of industry, government, and security that—through collaborative means—the effectiveness of the international nonproliferation system—can be most effectively strengthened to the mutual benefit of both government and the private sector. Industry has a critical stake in the success of this regime, and has the potential to act as an integrating force that brings together the existing mechanisms of the global nonproliferation regime: export controls, physical protection, and safeguards. The authors conclude that industry compliance is not enough; rather, nonproliferation must become a central tenant of a company’s corporate culture and be viewed as an integral component of corporate social responsibility (CSR).

  11. Management Principles for Nonproliferation Organizations

    Energy Technology Data Exchange (ETDEWEB)

    Frazar, Sarah L.; Hund, Gretchen

    2012-03-06

    This paper identifies business models and six management principles that can be applied by a nonproliferation organization to maximize the value and effectiveness of its products. The organizations responsible for reducing the nuclear proliferation threat have experienced a substantial growth in responsibility and visibility since the September 11 attacks. Since then, the international community has witnessed revelations of clandestine nuclear facilities, nuclear black markets, periodic nuclear tests, and a resurgence of interest by countries worldwide in developing nuclear capabilities. The security environment will likely continue to evolve in unexpected ways since most of the proliferation threats with which the world will be forced to contend remain unforeseen. To better prepare for and respond to this evolving security environment, many nonproliferation organizations are interested in finding new or better ways to increase the effectiveness and efficiency of their operations. Of course, all organizations, whether they are market driven or non-profit, must operate effectively and efficiently if they are to succeed. Indeed, as this study demonstrates, many of the management principles that this study recommends can help all organizations succeed. However, this study pays particular attention to nonproliferation organizations because of the mission they are responsible for fulfilling. Nonproliferation organizations, including nonproliferation programs that operate within a larger national security organization, are responsible for reducing the threat of nuclear, chemical and biological weapons. These organizations have an enduring mandate from the public and the international community not to fail in the completion of their mission for failure could have detrimental impacts on international security, public health and the environment. Moreover, the public expects nonproliferation organizations and programs to fulfill their mission, even when resources are limited

  12. A Digest of Nonproliferation Literature.

    Energy Technology Data Exchange (ETDEWEB)

    Duggan, Ruth A

    2006-04-01

    In preparation for the 2005 US/Russian Weapons Laboratories Directors Meeting, the six laboratories participating in the meeting endeavored to develop a strategy for nonproliferation technology research and development. A literature review was conducted to identify possible areas of technical collaboration and technology opportunities associated with improving nonproliferation associated with the civilian nuclear fuel cycle. The issue of multinationalization of the nuclear fuel cycle was also researched. This digest is the compilation of one-page summaries used by management of the three US nuclear weapons laboratories in preparation for strategy development. Where possible, the Web site address of the complete paper is referenced.3 AcknowledgementsThe author wishes to thank Jessica Ruyle, Nancy Orlando-Gay, and Barbara Dry for their research assistance and contributions.4

  13. 75 FR 28672 - Bureau of International Security and Nonproliferation; Lifting of Nonproliferation Measures...

    Science.gov (United States)

    2010-05-21

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Bureau of International Security and Nonproliferation; Lifting of Nonproliferation Measures Against Two... measures on two Russian entities. DATES: Effective Date: May 21, 2010. FOR FURTHER INFORMATION CONTACT...

  14. Nuclear World Order and Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Joeck, N

    2007-02-05

    The decision by India and Pakistan in May 1998 to conduct nuclear weapon tests and declare themselves as nuclear weapon states challenged South Asian regional stability calculations, US nonproliferation policy, and prevailing assumptions about international security. A decade later, the effects of those tests are still being felt and policies are still adjusting to the changed global conditions. This paper will consider non- and counter-proliferation policy options for the United States and Pakistan as they work as partners to prevent the transfer of nuclear technology and further nuclear proliferation.

  15. Handbook for nuclear non-proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Wook; Oh, Keun Bae; Lee, Kwang Seok; Lee, Dong Jin; Ko, Han Seok

    1997-05-01

    This book analyzed international non-proliferation regime preventing from spread of nuclear weapon. This book took review from the historical background of non-proliferation regime to the recent changes and status. The regime, here, is divided into multilateral and bilateral regime. First of all, this book reports four multilateral treaties concluded for non-proliferation such as NPT, NWFZ, CTBT and others. Secondly, international organization and regimes concerned with non-proliferation are analyzed with emphasis of UN, IAEA, ZC and NSG, Regional Safeguards System and international conference. Finally, this book report the current circumstances of nuclear cooperation agreement related with Korea which is an important means for bilateral regime. (author). 13 tabs., 2 figs.

  16. 20 CFR 668.710 - What planning documents must an INA grantee submit?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What planning documents must an INA grantee... LABOR INDIAN AND NATIVE AMERICAN PROGRAMS UNDER TITLE I OF THE WORKFORCE INVESTMENT ACT Section 166 Planning/Funding Process § 668.710 What planning documents must an INA grantee submit? Each...

  17. 20 CFR 668.840 - What cost principles apply to INA funds?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false What cost principles apply to INA funds? 668... INDIAN AND NATIVE AMERICAN PROGRAMS UNDER TITLE I OF THE WORKFORCE INVESTMENT ACT Administrative Requirements § 668.840 What cost principles apply to INA funds? The cost principles described in OMB...

  18. 20 CFR 668.930 - May INA grantees combine or consolidate their employment and training funds?

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false May INA grantees combine or consolidate their employment and training funds? 668.930 Section 668.930 Employees' Benefits EMPLOYMENT AND TRAINING... ACT Miscellaneous Program Provisions § 668.930 May INA grantees combine or consolidate...

  19. Technical solutions to nonproliferation challenges

    Science.gov (United States)

    Satkowiak, Lawrence

    2014-05-01

    The threat of nuclear terrorism is real and poses a significant challenge to both U.S. and global security. For terrorists, the challenge is not so much the actual design of an improvised nuclear device (IND) but more the acquisition of the special nuclear material (SNM), either highly enriched uranium (HEU) or plutonium, to make the fission weapon. This paper provides two examples of technical solutions that were developed in support of the nonproliferation objective of reducing the opportunity for acquisition of HEU. The first example reviews technologies used to monitor centrifuge enrichment plants to determine if there is any diversion of uranium materials or misuse of facilities to produce undeclared product. The discussion begins with a brief overview of the basics of uranium processing and enrichment. The role of the International Atomic Energy Agency (IAEA), its safeguard objectives and how the technology evolved to meet those objectives will be described. The second example focuses on technologies developed and deployed to monitor the blend down of 500 metric tons of HEU from Russia's dismantled nuclear weapons to reactor fuel or low enriched uranium (LEU) under the U.S.-Russia HEU Purchase Agreement. This reactor fuel was then purchased by U.S. fuel fabricators and provided about half the fuel for the domestic power reactors. The Department of Energy established the HEU Transparency Program to provide confidence that weapons usable HEU was being blended down and thus removed from any potential theft scenario. Two measurement technologies, an enrichment meter and a flow monitor, were combined into an automated blend down monitoring system (BDMS) and were deployed to four sites in Russia to provide 24/7 monitoring of the blend down. Data was downloaded and analyzed periodically by inspectors to provide the assurances required.

  20. NATO and nonproliferation: A critical appraisal

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, M.; Kelle, A.; Mueller, H.

    1994-04-01

    This paper analyses NATO`s past, actual and potential impact on the nonproliferation regime. It starts by looking back at the useful function NATO has performed throughout its existence in discouraging motivations by its non-nuclear weapon member-states from going nuclear. It then asks whether that role is likely to continue. The study goes on to ask whether NATO`s doctrine and practice may also pose risks to the regime, and investigates what benefits and risks may emerge from future counterproliferation activities. In conclusion, the paper suggests a modest but useful contribution NATO could make to strengthen the nonproliferation regime, provided major flaws are avoided. (orig.)

  1. Arms control and nonproliferation technologies: The non-proliferation experiment. First quarter 1994

    Energy Technology Data Exchange (ETDEWEB)

    Staehle, G.; Stull, S.; Talaber, C. [eds.

    1994-05-01

    In this issue of Arms Control and Nonproliferation Technologies we present the initial findings of the recent Non-Proliferation Experiment (NPE), conducted by the Department of Energy at the Nevada Test Site. Through an introduction and pictorial walk-through, Marv Denny and Jay Zucca of Lawrence Livermore National Laboratory describe the overall experiment. This is followed by scientific and technical abstracts of the complex suite of experiments and analyses, which were presented at the Symposium on Non-Proliferation Experiment Results and Implications for Test Ban Treaties, April 19--21, 1994. Questions regarding the ongoing analysis and conclusions from the NPE should be directed to Leslie Casey in the Office of Research and Development within the Office of Nonproliferation and National Security of DOE. Her phone number is 202-586-2151.

  2. DETERMINATION OF RELATIVE IMPORTANCE OF NONPROLIFERATION FACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Richard Metcalf

    2009-07-01

    Methodologies to determine the proliferation resistance (PR) of nuclear facilities often rely on either expert elicitation, a resource-intensive approach without easily reproducible results, or numeric evaluations, which can fail to take into account the institutional knowledge and expert experience of the nonproliferation community. In an attempt to bridge the gap and bring the institutional knowledge into numeric evaluations of PR, a survey was conducted of 33 individuals to find the relative importance of a set of 62 nonproliferation factors, subsectioned into groups under the headings of Diversion, Transportation, Transformation, and Weaponization. One third of the respondents were self-described nonproliferation professionals, and the remaining two thirds were from secondary professions related to nonproliferation, such as industrial engineers or policy analysts. The factors were taken from previous work which used multi-attribute utility analysis with uniform weighting of attributes and did not include institutional knowledge. In both expert and non-expert groups, all four headings and the majority of factors had different relative importance at a confidence of 95% (p=0.05). This analysis and survey demonstrates that institutional knowledge can be brought into numeric evaluations of PR, if there is a sufficient investment of resources made prior to the evaluation.

  3. Systems resilience : a new analytical framework for nuclear nonproliferation.

    Energy Technology Data Exchange (ETDEWEB)

    Pregenzer, Arian Leigh

    2011-12-01

    This paper introduces the concept of systems resilience as a new framework for thinking about the future of nonproliferation. Resilience refers to the ability of a system to maintain its vital functions in the face of continuous and unpredictable change. The nonproliferation regime can be viewed as a complex system, and key themes from the literature on systems resilience can be applied to the nonproliferation system. Most existing nonproliferation strategies are aimed at stability rather than resilience, and the current nonproliferation system may be over-constrained by the cumulative evolution of strategies, increasing its vulnerability to collapse. The resilience of the nonproliferation system can be enhanced by diversifying nonproliferation strategies to include general international capabilities to respond to proliferation and focusing more attention on reducing the motivation to acquire nuclear weapons in the first place. Ideas for future research, include understanding unintended consequences and feedbacks among nonproliferation strategies, developing methodologies for measuring the resilience of the nonproliferation system, and accounting for interactions of the nonproliferation system with other systems on larger and smaller scales.

  4. Nonproliferation Graduate Fellowship Program Annual Report: Class of 2011

    Energy Technology Data Exchange (ETDEWEB)

    McMakin, Andrea H.

    2012-08-20

    Annual report for the Nonproliferation Graduate Fellowship Program (NGFP), which PNNL administers for the National Nuclear Security Administration (NNSA). Features the Class of 2011. The NGFP is a NNSA program with a mission to cultivate future technical and policy leaders in nonproliferation and international security. Through the NGFP, outstanding graduate students with career interests in nonproliferation are appointed to program offices within the Office of Defense Nuclear Nonproliferation (DNN). During their one-year assignment, Fellows participate in programs designed to detect, prevent, and reverse the proliferation of nuclear weapons.

  5. Nuclear trade and non-proliferation: report by working group; Commerce nucleaire et non-proliferation: rapport du groupe de travail

    Energy Technology Data Exchange (ETDEWEB)

    Kerever, M.

    1995-12-31

    The paper is organized in three parts. The first one analyses the Treaty on the Non-proliferation of Nuclear Weapons (NPT) mentioning the arrangements and registered agreements between the IAEA and Member States. Also, the most important international legal instruments concerned the peaceful uses of nuclear energy are considered. In the second part, other international, regional or national legal instruments are discussed, particularly the London Club Guidelines, Treaty of Tlatelolco, the EURATOM and the Commission of the European Communities (CEC) Treaties, besides the American law of 18 Mars, 1978 - Nuclear Non-proliferation Act (NNPA) about the exportation of materials and services or nuclear technology; An appreciation about the laws and treaties are presented in the third part. Special attention is given to reinforce the non-proliferation dispositives face the actions after Iraq`s event (1990): new installations and nuclear activities moratorium extension export controls extension established by the London Club Guidelines and full scope safeguards adoption to accomplish controls and protect of dual-use nuclear-related technologies. 3 refs.

  6. Developing Effluent Analysis Technologies to Support Nonproliferation Initiatives, Arms Control and Nonproliferation Technologies, Third quarter 1995

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, S A; Staehle, G; Alonzo, G M [eds.

    1995-01-01

    This issue provides an overview of the Effluent Research Program of the DOE Office of Research and Development, highlighting a number of representative projects within this program in support of nonproliferation initiatives. Technologies reported include portable instruments for on-site inspections, standoff detectors, fieldable, real-time instruments, field collection techniques, and ultrasensitive laboratory techniques.

  7. Nuclear Nonproliferation Ontology Assessment Team Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Strasburg, Jana D.; Hohimer, Ryan E.

    2012-01-01

    Final Report for the NA22 Simulations, Algorithm and Modeling (SAM) Ontology Assessment Team's efforts from FY09-FY11. The Ontology Assessment Team began in May 2009 and concluded in September 2011. During this two-year time frame, the Ontology Assessment team had two objectives: (1) Assessing the utility of knowledge representation and semantic technologies for addressing nuclear nonproliferation challenges; and (2) Developing ontological support tools that would provide a framework for integrating across the Simulation, Algorithm and Modeling (SAM) program. The SAM Program was going through a large assessment and strategic planning effort during this time and as a result, the relative importance of these two objectives changed, altering the focus of the Ontology Assessment Team. In the end, the team conducted an assessment of the state of art, created an annotated bibliography, and developed a series of ontological support tools, demonstrations and presentations. A total of more than 35 individuals from 12 different research institutions participated in the Ontology Assessment Team. These included subject matter experts in several nuclear nonproliferation-related domains as well as experts in semantic technologies. Despite the diverse backgrounds and perspectives, the Ontology Assessment team functioned very well together and aspects could serve as a model for future inter-laboratory collaborations and working groups. While the team encountered several challenges and learned many lessons along the way, the Ontology Assessment effort was ultimately a success that led to several multi-lab research projects and opened up a new area of scientific exploration within the Office of Nuclear Nonproliferation and Verification.

  8. Evolution and resilience of the nuclear nonproliferation regime

    Energy Technology Data Exchange (ETDEWEB)

    Pregenzer, Arian L. [Senior Scientist, Retired, Sandia National Laboratories, 13013 Arroyo de Vista NE, Albuquerque, NM 87111 (United States)

    2014-05-09

    This paper introduces the concept of systems resilience as a new framework for thinking about the future of the nonproliferation regime. Resilience refers to the ability of a system to maintain its vital functions in the face of continuous and unpredictable change. First, I make the case that the nonproliferation regime can be viewed as a complex system. Next, I discuss key themes from the literature on systems resilience and apply them to the nonproliferation system: the difference between resilience and stability; the need for evolution to maintain function; the importance of functional diversity; and the concept of the adaptive cycle. I show that most existing nonproliferation strategies are aimed at stability rather than resilience and that the current nonproliferation system may be over-constrained by the cumulative evolution of strategies. According to the literature on systems resilience, this increases its vulnerability to collapse. I argue that the resilience of the nonproliferation system can be enhanced by increasing international participation in setting the nonproliferation agenda, developing general international response capabilities, focusing on non-coercive approaches to decreasing demand, and applying systems thinking more rigorously to nonproliferation.

  9. The Nuclear Nonproliferation Treaty in Context

    Science.gov (United States)

    Davenport, Kelsey

    2017-01-01

    The 1968 Nuclear Nonproliferation Treaty (NPT) is the cornerstone of multilateral efforts to prevent the spread of nuclear weapons and promote efforts toward complete disarmament. In the grand bargain of the NPT, states foreswore pursuit of nuclear weapons in exchange for access to nuclear technology and limited nuclear arsenals to the five states (China, France, Russia, the United Kingdom and the United States) that tested such weapons before the NPT's conception. Now in its seventh decade, the NPT regime is embraced by the vast majority of the world's nations and is viewed as a critical element of international security. However, despite past successes in halting efforts in several states to pursue nuclear weapons, near universal adherence, and only one withdrawal (North Korea), the NPT regime is at a critical crossroads. The treaty has proven unable to adapt to new challenges, such as emerging technologies that threaten operational strategic realities, the devolution of state authority to non-state actors and institutions, and growing dissatisfaction with slow pace of nuclear disarmament. Additionally, the treaty leaves open critical questions, including whether or not state parties have the `right' to pursue technologies that allow for domestic production of fuels for nuclear reactors and if modernization programs for nuclear warheads are inconsistent with the treaty. If these questions remain unresolved, the international community will find itself ill prepared to confront emerging proliferation challenges and the NPT, the linchpin of international nonproliferation and disarmament efforts, may begin to erode.

  10. The Nuclear Non-Proliferation Policy of the Obama Administration

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Jin Hyun; Hwang, Ji Hwan [Haesung International Problem Ethics Research Institute, Seoul (Korea, Republic of)

    2009-12-15

    The objective of this study is to analyze and foresee trends of international nuclear non-proliferation regimes focused on the nuclear non-proliferation policy of the Obama administration, and suggest national policy directions which promote utilization and development of nuclear energy in Korea. For the effective and efficient implementation of the national nuclear use and development program in current international nuclear environment, many efforts should be made: to actively and positively participate in the international nuclear non-proliferation regime; to strengthen nuclear diplomacy in a more systematic manner; and to strengthen the international nuclear cooperation

  11. Nuclear Deterrence in the Age of Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, J

    2009-01-21

    The fallacy of zero nuclear weapons, even as a virtual goal, is discussed. Because the complete abolition of nuclear weapons is not verifiable, nuclear weapons will always play a role in the calculus of assure, dissuade, deter and defeat (ADDD). However, the relative contribution of nuclear weapons to international security has diminished. To reconstitute the Cold War nuclear capability, with respect to both the nuclear weapons capability and their associated delivery systems, is fiscally daunting and not warranted due to competing budgetary pressures and their relative contribution to international security and nonproliferation. A proposed pathway to a sustainable nuclear weapons capability end-state is suggested which provides enough ADDD; a Dyad composed of fewer delivery and weapon systems, with trickle production at the National Laboratories and private sector to maintain capability and guard against technological surprise.

  12. Workshop on nuclear power growth and nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Pilat, Joseph F [Los Alamos National Laboratory

    2010-01-01

    It is widely viewed that an expansion of nuclear power would have positive energy, economic and environmental benefits for the world. However, there are concerns about the economic competitiveness, safety and proliferation and terrorism risks of nuclear power. The prospects for a dramatic growth in nuclear power will depend on the ability of governments and industry to address these concerns, including the effectiveness of, and the resources devoted to, plans to develop and implement technologies and approaches that strengthen nonproliferation, nuclear materials accountability and nuclear security. In his Prague speech, President Obama stated: 'we should build a new framework for civil nuclear cooperation, including an international fuel bank, so that countries can access peaceful power without increasing the risks of proliferation. That must be the right of every nation that renounces nuclear weapons, especially developing countries embarking on peaceful programs. And no approach will succeed if it's based on the denial of rights to nations that play by the rules. We must harness the power of nuclear energy on behalf of our efforts to combat climate change, and to advance peace opportunity for all people.' How can the President's vision, which will rekindle a vigorous public debate over the future of nuclear power and its relation to proliferation, be realized? What critical issues will frame the reemerging debate? What policies must be put into place to address these issues? Will US policy be marked more by continuity or change? To address these and other questions, the Los Alamos National Laboratory in cooperation with the Woodrow Wilson International Center for Scholars will host a workshop on the future of nuclear power and nonproliferation.

  13. IAEA safeguards and non-proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Harry, R.J.S.

    1995-02-01

    An overview is given of efforts to contain the nuclear weapons proliferation during half a century of man-controlled nuclear fission. An initial policy of denial did not work, a following period of cooperation needed a gradual strengthening of international assurances on the peaceful character of the flourishing use of nuclear techniques for power generation and of other applications. The focus of the nuclear weapon proliferation concern changed from the highly developed states to developing states. The Non-Proliferation Treaty laid the basis for a unique system of voluntarily accepted international inspections to verify the peaceful use of nuclear energy. The IAEA got the task to implement this `Full Scope Safeguards` on all nuclear material and all nuclear activities in the non-nuclear weapon states. Thanks to the structure of the IAEA, in which both proponent and states with a critical attitude take part in the decision making process on the IAEA execution of its tasks, a balanced, and widely acceptable system emerged. International developments necessitated additional improvements of the non-proliferation system. The increase of strength of sub-national groups triggered international cooperation on physical protection, about a quarter of a century ago. More recently, it appeared that NPT states with assumed nuclear weapon ambitions operated in the margins between the interpretation of IAEA safeguards and the spirit and purpose of NPT. Improvements of the IAEA safeguards and a stronger cooperation between states, including the constraints which exporting states have imposed on nuclear supplies, strengthen the safeguards system. The important reductions in the two largest nuclear weapon arsenals lead, together with the delay in the fast breeder implementation, to large stockpiles of nuclear weapon usable materials. Also in this areas new internationally credible assurances have to be obtained, that these materials will never return to nuclear weapon applications.

  14. InaSAFE applications in disaster preparedness

    Science.gov (United States)

    Pranantyo, Ignatius Ryan; Fadmastuti, Mahardika; Chandra, Fredy

    2015-04-01

    Disaster preparedness activities aim to reduce the impact of disasters by being better prepared to respond when a disaster occurs. In order to better anticipate requirements during a disaster, contingency planning activities can be undertaken prior to a disaster based on a realistic disaster scenario. InaSAFE is a tool that can inform this process. InaSAFE is a free and open source software that estimates the impact to people and infrastructure from potential hazard scenarios. By using InaSAFE, disaster managers can develop scenarios of disaster impacts (people and infrastructures affected) to inform their contingency plan and emergency response operation plan. While InaSAFE provides the software framework exposure data and hazard data are needed as inputs to run this software. Then InaSAFE can be used to forecast the impact of the hazard scenario to the exposure data. InaSAFE outputs include estimates of the number of people, buildings and roads are affected, list of minimum needs (rice and clean water), and response checklist. InaSAFE is developed by Indonesia's National Disaster Management Agency (BNPB) and the Australian Government, through the Australia-Indonesia Facility for Disaster Reduction (AIFDR), in partnership with the World Bank - Global Facility for Disaster Reduction and Recovery (GFDRR). This software has been used in many parts of Indonesia, including Padang, Maumere, Jakarta, and Slamet Mountain for emergency response and contingency planning.

  15. Nuclear Nonproliferation Policy Issues in the 103rd Congress

    Science.gov (United States)

    2016-03-24

    North Korea Former Soviet Weapons President Clinton’s Address to the U.N. Federal Organization for Nonproliferation Counterproliferation Export ...Nonproliferation Policy Congress Weapon International North Korea Former Soviet Union Clinton Counterproliferation Export Control Short Long Term Issue Pages: 14...include: (1) proliferation efforts. These include the North Korea’s violation of its NPT obliga- agreement by Argentina and Brazil to allow tions; (2

  16. Modeling and Simulation for Safeguards and Nonproliferation Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Gilligan, Kimberly V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kirk, Bernadette Lugue [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-01-01

    The Modeling and Simulation for Safeguards and Nonproliferation Workshop was held December 15–18, 2014, at Oak Ridge National Laboratory. This workshop was made possible by the Next Generation Safeguards Initiative Human Capital Development (NGSI HCD) Program. The idea of the workshop was to move beyond the tried-and-true boot camp training of nonproliferation concepts to spend several days on the unique perspective of applying modeling and simulation (M&S) solutions to safeguards challenges.

  17. Development of nonproliferation and assessment scenarios.

    Energy Technology Data Exchange (ETDEWEB)

    Finley, Melissa; Barnett, Natalie Beth

    2005-10-01

    The overall objective of the Nonproliferation and Assessments Scenario Development project is to create and analyze potential and plausible scenarios that would lead to an adversary's ability to acquire and use a biological weapon. The initial three months of funding was intended to be used to develop a scenario to demonstrate the efficacy of this analysis methodology; however, it was determined that a substantial amount of preliminary data collection would be needed before a proof of concept scenario could be developed. We have dedicated substantial effort to determine the acquisition pathways for Foot and Mouth Disease Virus, and similar processes will be applied to all pathogens of interest. We have developed a biosecurity assessments database to capture information on adversary skill locales, available skill sets in specific regions, pathogen sources and regulations involved in pathogen acquisition from legitimate facilities. FY06 funding, once released, will be dedicated to data collection on acquisition, production and dissemination requirements on a pathogen basis. Once pathogen data has been collected, scenarios will be developed and scored.

  18. La costituzione dell’INA e il monopolio statale delle assicurazioni (1912-1922 = The constitution of INA and the state monopoly of insurance (1912-1922

    Directory of Open Access Journals (Sweden)

    Serena Potito

    2012-07-01

    Full Text Available Il saggio –basato principalmente su documenti attualmente conservati presso l’Archivio Storico dell’INA, a Roma– esamina le vicende legate alla nascita dell’Istituto, costituito in un regime transitorio di monopolio relativo nel settore delle assicurazioni sulla vita.A causa del suo significato economico e politico, questa speciale forma di monopolio statale diede luogo a molte reazioni nell’ambito finanziario e politico nazionale, pertanto l’INA iniziò i primi anni di attività in una situazione conflittuale ed incerta.Il saggio inoltre approfondisce le ripercussioni sul mercato assicurativo internazionale in seguito alla nascita dell’INA.Durante il decennio di monopolio parziale dell’Istituto nel settore delle assicurazioni sulla vita (1912-1922, le compagnie di assicurazione straniere ritennero compromessi i loro interessi finanziari nel mercato italiano, e lo osteggiarono fino al 1923, quando una nuova legge riformò il mercato assicurativo sulla vita, abolendo il regime di monopolio.The essay –mainly based on documents actually preserved in the Historical Archives of INA, in Rome– examines the events connected with the foundation of the Institute, established in a transient condition of partial monopoly system in life insurance sector. Because of its economic and political meaning, this special form of state monopoly gave rise to many reactions in the financial and political national context, and so INA started its first years of activity in a troubled and unstable situation. The essay also discusses about the repercussions on international insurance market in consequence of the foundation of INA.During the ten-year perior of partial monopoly of the Institute in life insurance sector (1912-1922, foreign insurance companies deemed their financial interest in Italian market jeopardized, and contrasted with it until 1923, when a new act reformed life insurance market, abrogating monopoly system. 

  19. 76 FR 68809 - Bureau of International Security and Nonproliferation; Termination of Chemical and Biological...

    Science.gov (United States)

    2011-11-07

    ... Nonproliferation; Termination of Chemical and Biological Weapons (CBW) Proliferation Sanctions Against a Foreign... CONTACT: Pamela K. Durham, Office of Missile, Biological, and Chemical Nonproliferation, Bureau of... government, project, or entity in its efforts to acquire chemical or biological weapons capability:...

  20. Chemical and biological nonproliferation program. FY99 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This document is the first of what will become an annual report documenting the progress made by the Chemical and Biological Nonproliferation Program (CBNP). It is intended to be a summary of the program's activities that will be of interest to both policy and technical audiences. This report and the annual CBNP Summer Review Meeting are important vehicles for communication with the broader chemical and biological defense and nonproliferation communities. The Chemical and Biological Nonproliferation Program Strategic Plan is also available and provides additional detail on the program's context and goals. The body of the report consists of an overview of the program's philosophy, goals and recent progress in the major program areas. In addition, an appendix is provided with more detailed project summaries that will be of interest to the technical community.

  1. University-level Non-proliferation and Safeguards Education and Human Capital Development Activities at Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Bachner K. M.; Pepper, S.; Gomera, J.; Einwechter, M.; Toler, L. T.

    2016-07-24

    BNL has offered Nuclear Nonproliferation, Safeguards and Security in the 21st Century,? referred to as NNSS, every year since 2009 for graduate students in technical and policy fields related to nuclear safeguards and nonproliferation. The course focuses on relevant policy issues, in addition to technical components, and is part of a larger NGSI short course initiative that includes separate courses that are delivered at three other national laboratories and NNSA headquarters. [SCHOLZ and ROSENTHAL] The course includes lectures from esteemed nonproliferation experts, tours of various BNL facilities and laboratories, and in-field and table-top exercises on both technical and policy subjects. Topics include the history of the Treaty on the Non-proliferation of Nuclear Weapons (NPT) and other relevant treaties, the history of and advances in international nuclear safeguards, current relevant political situations in countries such as Iran, Iraq, and the Democratic Peoples? Republic of Korea (DPRK), nuclear science and technology, instrumentation and techniques used for verification activities, and associated research and development. The students conduct a mock Design Information Verification (DIV) at BNL?s decommissioned Medical Research Reactor. The capstone of the course includes a series of student presentations in which students act as policy advisors and provide recommendations in response to scenarios involving a current nonproliferation related event that are prepared by the course organizers. ?The course is open to domestic and foreign students, and caters to students in, entering, or recently having completed graduate school. Interested students must complete an application and provide a resume and a statement describing their interest in the course. Eighteen to 22 students attend annually; 165 students have completed the course to date. A stipend helps to defray students? travel and subsistence expenses. In 2015, the course was shortened from three weeks to

  2. Nonproliferation Graduate Fellowship Program, Annual Report, Class of 2012

    Energy Technology Data Exchange (ETDEWEB)

    McMakin, Andrea H.

    2013-09-23

    This 32-pp annual report/brochure describes the accomplishments of the Class of 2012 of the Nonproliferation Graduate Fellowship Program (the last class of this program), which PNNL administers for the National Nuclear Security Administration. The time period covers Sept 2011 through June 2013.

  3. Nonproliferation and safeguards aspects of the DUPIC fuel cycle concept

    Energy Technology Data Exchange (ETDEWEB)

    Persiani, P. K. [Argonne National Lab., IL (United States)

    1997-07-01

    The purpose of the study is to comment on the proliferation characteristic profiles of some of the proposed fuel cycle alternatives to help ensure that nonproliferation concerns are introduced into the early stages of a fuel cycle concept development program, and to perhaps aid in the more effective implementation of the international nonproliferation regime initiative and safeguards systems. Alternative recycle concepts proposed by several countries involve the recycle of spent fuel without the separation of plutonium from uranium and fission products. The concepts are alternatives to either the direct long-term storage deposition of or the purex reprocessing of the spent fuels. The alternate fuel cycle concepts reviewed include: the dry-recycle processes such as the direct use of reconfigured PWR spent fuel assemblies into CANDU reactors(DUPIC); low-decontamination, single-cycle co-extraction of fast reactor fuels in a wet-purex type of reprocessing; and on a limited scale the thorium-uranium fuel cycle. The nonproliferation advantages usually associated with the above non-separation processes are: the highly radioactive spent fuel presents a barrier to the physical diversion of the nuclear material; avoid the need to dissolve and chemically separate the plutonium from the uranium and fission products; and that the spent fuel isotopic quality of the plutonium vector is further degraded. Although the radiation levels and the need for reprocessing may be perceived as barriers to the terrorist or the subnational level of safeguards, the international level of nonproliferation concerns is addressed primarily by material accountancy and verification activities. On the international level of nonproliferation concerns, the non-separation fuel cycle concepts involved have to be evaluated on the bases of the impact the processes may have on nuclear materials accountancy. (author).

  4. Simple intrinsic defects in InAs :

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Peter Andrew

    2013-03-01

    This Report presents numerical tables summarizing properties of intrinsic defects in indium arsenide, InAs, as computed by density functional theory using semi-local density functionals, intended for use as reference tables for a defect physics package in device models.

  5. Identification of Ina proteins from Fusarium acuminatum

    Science.gov (United States)

    Scheel, Jan Frederik; Kunert, Anna Theresa; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

    2015-04-01

    Freezing of water above -36° C is based on ice nucleation activity (INA) mediated by ice nucleators (IN) which can be of various origins. Beside mineral IN, biological particles are a potentially important source of atmospheric IN. The best-known biological IN are common plant-associated bacteria. The IN activity of these bacteria is induced by a surface protein on the outer cell membrane, which is fully characterized. In contrast, much less is known about the nature of fungal IN. The fungal genus Fusarium is widely spread throughout the earth. It belongs to the Ascomycota and is one of the most severe fungal pathogens. It can affect a variety of organisms from plants to animals including humans. INA of Fusarium was already described about 30 years ago and INA of Fusarium as well as other fungal genera is assumed to be mediated by proteins or at least to contain a proteinaceous compound. Although many efforts were made the precise INA machinery of Fusarium and other fungal species including the proteins and their corresponding genes remain unidentified. In this study preparations from living fungal samples of F. acuminatum were fractionated by liquid chromatography and IN active fractions were identified by freezing assays. SDS-page and de novo sequencing by mass spectrometry were used to identify the primary structure of the protein. Preliminary results show that the INA protein of F. acuminatum is contained in the early size exclusion chromatography fractions indicating a high molecular size. Moreover we could identify a single protein band from IN active fractions at 130-145 kDa corresponding to sizes of IN proteins from bacterial species. To our knowledge this is for the first time an isolation of a single protein from in vivo samples, which can be assigned as IN active from Fusarium.

  6. Latin America`s emerging non-proliferation consensus

    Energy Technology Data Exchange (ETDEWEB)

    Redick, J.R.

    1994-03-01

    Latin America`s incorporation into the international nuclear non-proliferation regime is well advanced. The 1967 Tlatelolco Treaty, which established a regional nuclear-weapon-free zone (NWFZ), is nearing completion. A signal event occurred January 18, when Argentina and Chile deposited instruments of ratification to the treaty, leaving Brazil and Cuba the only major countries in Latin America that are not yet contracting parties. And after more than two decades of concern about the nuclear programs and policies in Argentina and Brazil, there is room for great optimism that Brazil may now be moving quickly on important non-proliferation issues. Even Cuba, the {open_quotes}bad boy of the neighborhood{close_quotes} in the eyes of many, which held aloof from the Tlatelolco process for three decades, has stated its willingness to join the zone in the future.

  7. An Introduction to Nuclear Non-Proliferation and Safeguards

    Energy Technology Data Exchange (ETDEWEB)

    Haakansson, Ane; Jonter, Thomas

    2007-06-15

    The purpose of this project was to compile a course material that covers how the nuclear safeguards system has emerged and how it works today. The produced compendium is directed to both university students and people concerned by safeguards from the industry. The primary aim of the first part of this paper is to describe the historical development of this global non-proliferation system and its central tasks. A second purpose is to discuss the advantages and disadvantages of its current design in order to answer the following question: Can we today say that we have a functioning global non-proliferation system? Does it require further strengthening, and, if so, how can this be achieved? In the second section we review the verification regime within nuclear safeguards, i. e. describe the methods and techniques that are available to reassure the world community that concluded treaties are adhered to

  8. 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.

  9. Influence of InAs deposition thickness on the structural and optical properties of InAs quantum wires

    Institute of Scientific and Technical Information of China (English)

    Yuanli Wang; Hua Cui; Wen Lei; Yahong Su; Yonghai Chen; Ju Wu; Zhanguo Wang

    2007-01-01

    The influence of InAs deposition thickness on the structural and optical properties of InAs/InAlAs quantum wires (QWR) superlattices (SLS) was studied. The transmission electron microscopy (TEM) results show that with increasing the InAs deposited thickness, the size uniformity and spatial ordering of InAs QWR SLS was greatly improved, but threading dislocations initiated from InAs nanowires for the sample with 6 monolayers (MLs) InAs deposition. In addition, the zig-zag features along the extending direction and lateral interlink of InAs nanowires were also observed. The InAs nanowires, especially for the first period, were laterally compact. These structural features may result in easy tunneling and coupling of charge carriers between InAs nanowires and will hamper their device applications to some extent. Some suggestions are put forward for further improving the uniformity of the stacked InAs QWRs, and for suppressing the formation of the threading dislocations in InAs QWR SLS.

  10. INTEGRATION OF FACILITY MODELING CAPABILITIES FOR NUCLEAR NONPROLIFERATION ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Gorensek, M.; Hamm, L.; Garcia, H.; Burr, T.; Coles, G.; Edmunds, T.; Garrett, A.; Krebs, J.; Kress, R.; Lamberti, V.; Schoenwald, D.; Tzanos, C.; Ward, R.

    2011-07-18

    Developing automated methods for data collection and analysis that can facilitate nuclear nonproliferation assessment is an important research area with significant consequences for the effective global deployment of nuclear energy. Facility modeling that can integrate and interpret observations collected from monitored facilities in order to ascertain their functional details will be a critical element of these methods. Although improvements are continually sought, existing facility modeling tools can characterize all aspects of reactor operations and the majority of nuclear fuel cycle processing steps, and include algorithms for data processing and interpretation. Assessing nonproliferation status is challenging because observations can come from many sources, including local and remote sensors that monitor facility operations, as well as open sources that provide specific business information about the monitored facilities, and can be of many different types. Although many current facility models are capable of analyzing large amounts of information, they have not been integrated in an analyst-friendly manner. This paper addresses some of these facility modeling capabilities and illustrates how they could be integrated and utilized for nonproliferation analysis. The inverse problem of inferring facility conditions based on collected observations is described, along with a proposed architecture and computer framework for utilizing facility modeling tools. After considering a representative sampling of key facility modeling capabilities, the proposed integration framework is illustrated with several examples.

  11. On the U.S. Post-Cold War Non-proliferation Policy

    Institute of Scientific and Technical Information of China (English)

    Liu; Zikui

    2014-01-01

    Since the end of the Cold War, the importance of non-proliferation of weapons of mass destruction(WMD) has been enhanced constantly in the U.S. national security strategy and on the agenda of the U.S. foreign policy, and non-proliferation gradually has becomes one of its most important policy objectives. As the sole superpower, the U.S. non-proliferation policy has not only influenced and changed the international non-proliferation regime dramatically, but also greatly affected the non-proliferation effect of the international community. To prevent WMD proliferation, the United States has to abandon the practice of selective non-proliferation, group politics, prejudice on different ideologies and social systems, and maintenance of the U.S. hegemony. While pursuing its and allies interests, it must also attach great importance to other countries interests.

  12. Nexus between directionality of THz waves and structural parameters in groove-patterned InAs

    CERN Document Server

    Yim, Jong-Hyuk; Jeong, Hoonil; Song, Jin-Dong; Jho, Young-Dahl

    2012-01-01

    We have performed terahertz (THz)-time domain spectroscopy in various geometries, for characterizing the directivity of THz waves emitted from groove-patterned InAs structures. First, we have distinguished the THz emission mechanisms as a function of epilayer thickness. The carrier drift was predominant in thin sample group (10-70 nm) which the electronic diffusion motion was overriding the oppositely aligned drifting dipoles in thick sample group (370-900 nm) as revealed via amplitude and phase variations. By combined use of the electron-beam lithography and the inductively coupled plasma etching in 1 {\\mu}m-thick InAs epilayers, we have further fabricated either asymmetric V-groove patterns or symmetric parabolic patterns. The THz amplitude was enhanced, particularly along line-of-sight transmissive direction when the groove patterns act as microscale reflective mirrors periodically separated by a scale of diffusion length.

  13. Considerations on nonproliferation regime meeting in a changing world

    Energy Technology Data Exchange (ETDEWEB)

    Kurihara, Hiroyoshi; Kikuchi, Masahiro [Nuclear Material Control Center, Tokyo (Japan)

    1994-12-31

    This paper summarizes the past history of worldwide nonproliferation regime, then proposes the future improvements on the regime. Present worldwide nonproliferation regime have been formulated during the cold war era. Therefore, the structure and measures of the regime were heavily influenced by the features of cold war era. Though the cold war was over, still new international order does not seem to be on the horizon, we need to review the present regime and to improve the regime compatible to new world situation. Generally speaking, the nonproliferation regime have gained moderate success so far. We could point out the following features as a kind of success: (1) No increase of overt Nuclear Weapon State (NWS), (2) All five NWSs have finally participated to the NPT, (3) South Africa has destroyed its nuclear weapons and became Non-Nuclear Weapon State (NNWS), (4) Successful conclusions of some regional arrangements, such as Tlatelolco, Ralotonga, and (5) Strengthening of export control on sensitive items. On the other hand, we recognize the following points as the failures of the regime. (6) India, Pakistan and Israel reject to join the NPT, (7) Existence of some violation against NPT regime, i.e. Iraqi case and DPRK case, (8) Insufficient effective measures against brain drain problem, (9) Risk exists for the long term extension of NPT, and (10) Insufficient flexibility to meet changing boundary conditions. We would propose the various measures for strengthening to meet changing boundary conditions, as follows: (11) Measures to be taken along with future civil use of Plutonium, (12) Strengthening and rationalizing international safeguards, (13) Countermeasures for emerging new types of nuclear proliferation, (14) Strengthening nuclear material control in NWS, (15) Measures to be taken for nuclear material from dismantled nuclear weapons, and (16) Nuclear disarmament. (author).

  14. Diameter-dependent conductance of InAs nanowires

    NARCIS (Netherlands)

    Scheffler, M.; Nadj-Perge, S.; Kouwenhoven, L.P.; Borgström, M.T.; Bakkers, E.P.A.M.

    2009-01-01

    Electrical conductance through InAs nanowires is relevant for electronic applications as well as for fundamental quantum experiments. Here, we employ nominally undoped, slightly tapered InAs nanowires to study the diameter dependence of their conductance. By contacting multiple sections of each wire

  15. Functionalized vertical InAs nanowire arrays for gas sensing

    NARCIS (Netherlands)

    Offermans, P.; Crego-Calama, M.; Brongersma, S.H.

    2012-01-01

    Vertical InAs nanowires are contacted in situ using an air-bridge construction and functionalized with a metalloporphyrin (Hemin). The response of bare and functionalized vertical InAs nanowire arrays to ppb-level concentrations of NO2 and NO is demonstrated. Hemin enhances the response to NO

  16. Saving the NPT: past and future non-proliferation bargains

    Energy Technology Data Exchange (ETDEWEB)

    Tertrais, B

    2005-07-01

    In this thorough study of the Nuclear Nonproliferation Treaty (NPT), the author looks at the origins of the NPT, its original bargains, and the current 'global crisis of compliance'. Then he looks to the 2005 NPT Review Conference for approaches 'to preserve the integrity and the credibility of the Treaty'. He suggests a new set of bargains centered around two issues: increase rewards for members in good standing of their obligations, but promote sanctions for those cheating; and recognize that nuclear disarmament is a distant goal, but satisfy the legitimate worries of NNWS (Non-Nuclear Weapon States)

  17. The Nuclear Non-Proliferation Treaty: Regulating Nuclear Weapons around the World

    Science.gov (United States)

    Middleton, Tiffany Willey

    2010-01-01

    In May 2010, scientists, national security experts, and state delegates from nations around the world will convene in New York for the 2010 Nuclear Non-Proliferation Treaty Review Conference. They will review current guidelines for nuclear testing and possession of nuclear weapons in accordance with the Nuclear Non-Proliferation Treaty of 1968,…

  18. The Nuclear Non-Proliferation Treaty: Regulating Nuclear Weapons around the World

    Science.gov (United States)

    Middleton, Tiffany Willey

    2010-01-01

    In May 2010, scientists, national security experts, and state delegates from nations around the world will convene in New York for the 2010 Nuclear Non-Proliferation Treaty Review Conference. They will review current guidelines for nuclear testing and possession of nuclear weapons in accordance with the Nuclear Non-Proliferation Treaty of 1968,…

  19. Detection Technologies, Arms control and nonproliferation technologies. Third/fourth quarters 1993

    Energy Technology Data Exchange (ETDEWEB)

    Staehle, G; Stull, S; Talaber, C; Moulthrop, P [eds.

    1993-12-31

    This issue of Arms Control and Nonproliferation Technologies is another in a series of issues about specific means for detecting and identifying proliferation and other suspect activities outside the realm of arms control treaties. All the projects discussed are funded by the Office of Research and Development of the Department of Energy`s Office of Nonproliferation and National Security.

  20. Electrical characterization of InAs thin films

    Energy Technology Data Exchange (ETDEWEB)

    Botha, L.; Shamba, P.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2008-07-01

    It is known that parallel conduction as a result of surface and /or interface charge accumulation significantly shields the bulk electrical properties of InAs thin films when characterized using Hall measurements. This parallel conduction in InAs can be modeled by using the two-layer model of Nedoluha and Koch [Zeitschrift fuer Physik 132, 608 (1952)]; where an InAs epilayer is treated as consisting of two conductors connected in parallel viz. a bulk and a surface layer. Here, this two-layer model is used to simulate Hall coefficient and conductivity data of InAs thin films ranging from strongly n-doped (n=10{sup 18} cm{sup -3}) to strongly p-doped (p{proportional_to}10{sup 19} cm{sup -3}) material. Conventional Hall approximations, i.e. those that assume uniform conduction from a single band, are then used to predict the apparent carrier concentration and mobility that will be determined from conventional Hall measurements, with the aim of illustrating the error of such a simplified analysis of InAs Hall data. Results show that, in addition to ignoring parallel conduction, the approximations of conventional Hall data analysis have a further inadequacy for p-type InAs, in that the high electron to hole mobility ratio in InAs is not taken into account. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. A study on the development of nuclear policy to respond to international non-proliferation regimes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Wook; Oh, K. B.; Yang, M. H.; Lee, H. M.; Ko, H. S.; Ryu, J. S.; Jung, W. H.; Lim, C. Y

    2006-01-15

    This study analyzed the trends of the nonproliferation regimes in the following three aspects. First, this study analyzed the trends of the international nuclear non-proliferation regime, which includes the NPT, the IAEA safeguards system, the international nuclear export control regime and multilateral nuclear approach. Second, this study forecast the future trends of the nonproliferation systems with the reflection of current international situations. Third, this study also analyzed outstanding issues in nuclear control regimes and derived some factors to reflect national nuclear foreign policy.

  2. Sharing knowledge, shaping Europe US technological collaboration and nonproliferation

    CERN Document Server

    Krige, John

    2016-01-01

    In the 1950s and the 1960s, U.S. administrations were determined to prevent Western European countries from developing independent national nuclear weapons programs. To do so, the United States attempted to use its technological pre-eminence as a tool of “soft power” to steer Western European technological choices toward the peaceful uses of the atom and of space, encouraging options that fostered collaboration, promoted nonproliferation, and defused challenges to U.S. technological superiority. In Sharing Knowledge, Shaping Europe, John Krige describes these efforts and the varying degrees of success they achieved. Krige explains that the pursuit of scientific and technological leadership, galvanized by America’s Cold War competition with the Soviet Union, was also used for techno-political collaboration with major allies. He examines a series of multinational arrangements involving shared technological platforms and aimed at curbing nuclear proliferation, and he describes the roles of the Department ...

  3. Improving Capture-gamma Libraries for Nonproliferation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Sleaford, Brad W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hurst, Aaron M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

    2016-11-01

    This report describes the measurement, evaluation and incorporation of new -ray spectroscopic data into the Evaluated Nuclear Data File (ENDF) for nonproliferation applications. Analysis and processing techniques are described along with key deliverables that have been met over the course of this project. A total of nine new ENDF libraries have been submitted to the National Nuclear Data Center at the Brookhaven National Laboratory and are now available in the ENDF/B-VIII.beta2 release. Furthermore, this project has led to more than ten peer-reviewed publications and provided theses for ve graduate students. This project is a component of the NA-22 venture collaboration on \\Correlated Nuclear Data in Fission Events" (LA14-V-CorrData-PD2Jb).

  4. Arms control and nonproliferation technologies. First quarter 1995

    Energy Technology Data Exchange (ETDEWEB)

    Staehle, G; Alonzo, G M; Sanford, N M [eds.

    1995-01-01

    This first quarter issue for 1995 highlights the Small Business Innovation Research (SBIR) program. The SBIR program is managed by the DOE`s Basic Energy Sciences program within the Office of Energy Research. Each year, the SBIR program solicits research ideas of interest to the DOE. Articles contained in this issue include: The Small Business Innovation Research Program supported by the Office of Nonproliferation and National Security; Automated cueing to man-made objects via multispectral image; Security systems get smart with advanced processing and thermal imaging; A breakthrough in cooling system technology; The APSTNG neutron probe; Lithium-doped fullerene neutron detector; Miniature GC-MS for on-site chemical analysis; and Winner of Sandia President`s Quality Award.

  5. Computer Language Choices in Arms Control and Nonproliferation Regimes

    Energy Technology Data Exchange (ETDEWEB)

    White, G K

    2005-06-10

    The U.S. and Russian Federation continue to make substantive progress in the arms control and nonproliferation transparency regimes. We are moving toward an implementation choice for creating radiation measurement systems that are transparent in both their design and in their implementation. In particular, the choice of a programming language to write software for such regimes can decrease or significantly increase the costs of authentication. In this paper, we compare procedural languages with object-oriented languages. In particular, we examine the C and C++ languages; we compare language features, code generation, implementation details, and executable size and demonstrate how these attributes aid or hinder authentication and backdoor threats. We show that programs in lower level, procedural languages are more easily authenticated than are object-oriented ones. Potential tools and methods for authentication are covered. Possible mitigations are suggested for using object-oriented programming languages.

  6. The presence of INA proteins on the surface of single cells of Pseudomonas syringae R10.79 isolated from rain

    Science.gov (United States)

    Šantl-Temkiv, Tina; Ling, Meilee; Holm, Stine; Finster, Kai; Boesen, Thomas

    2016-04-01

    our surprise, exposure of cells to low temperatures, which is normally considered to be the main driver of the INA protein synthesis, had no or even a negative effect on the proportion of cells with INA proteins. Our results suggest that at certain conditions a high proportion of Pseudomonas syringae cells produces INA proteins and that this proportion depends on the physiological state of the cells. This and similar studies will ultimately improve our understanding of the quantitative role bacterial INA proteins play in atmospheric processes. References DeMott, P., Prenni, A.J. (2010): New Directions: Need for defining the numbers and sources of biological aerosols acting as ice nuclei. Atmos Environ. doi: 10.1016/j.atmosenv.2010.02.032 Šantl-Temkiv, T., Sahyoun, M., Finster, K., Hartmann, S., Augustin-Bauditz, S, Stratmann, F. et al (2015): Characterization of airborne ice-nucleation-active bacteria and bacterial fragments. Atmos Environ. doi: ttp://doi.org/10.1016/j.atmosenv.2015.02.060

  7. Femtosecond upconverted photocurrent spectroscopy of InAs quantum nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yasuhiro [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Tex, David M.; Kanemitsu, Yoshihiko, E-mail: kanemitu@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Japan Science and Technology Agency, CREST, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kamiya, Itaru [Toyota Technological Institute, Nagoya, Aichi 468-8511 (Japan)

    2015-07-06

    The carrier upconversion dynamics in InAs quantum nanostructures are studied for intermediate-band solar-cell applications via ultrafast photoluminescence and photocurrent (PC) spectroscopy based on femtosecond excitation correlation (FEC) techniques. Strong upconverted PC-FEC signals are observed under resonant excitation of quantum well islands (QWIs), which are a few monolayer-thick InAs quantum nanostructures. The PC-FEC signal typically decays within a few hundred picoseconds at room temperature, which corresponds to the carrier lifetime in QWIs. The photoexcited electron and hole lifetimes in InAs QWIs are evaluated as functions of temperature and laser fluence. Our results provide solid evidence for electron–hole–hole Auger process, dominating the carrier upconversion in InAs QWIs at room temperature.

  8. Application of INPRO Methodology in Evaluation of Nonproliferation Features of TWR

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Through the once-through fuel cycle mode, the Traveling Wave Reactor (TWR) concept can utilize the uranium resources much effectively. The once-through fuel cycle has the inherent characteristics of the non-proliferation. In this project,

  9. Hall measurements on InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Bloemers, Christian; Grap, Thomas; Lepsa, Mihail I.; Gruetzmacher, Detlev; Lueth, Hans [Peter Gruenberg Institut (PGI-9), Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany); Trellenkamp, Stefan [Peter Gruenberg Institut (PGI-8), Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany); Schaepers, Thomas [Peter Gruenberg Institut (PGI-9), Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany); II. Physikalisches Institut, RWTH Aachen, 52074 Aachen (Germany)

    2012-07-01

    In search of novel concepts for the realization of nanoelectronic devices, semiconductor nanowires grown by ''bottom-up'' techniques have shown great promise. Without any doubt, the knowledge about the free carrier concentration n{sub el} is crucial for the fabrication of such devices on the nanometer scale. The most common method to determine n{sub el} in nanowires is to utilize the field effect in a gate measurement setup. However, within this method, uncertainties such as the density of surface states between the nanowire and the dielectric material or the resulting nanowire capacitance influence results. Additionally, source and drain electrodes tend to screen the gate potential in devices of small size. Here we report on Hall measurements on InAs nanowires as an alternative method to determine n{sub el}. By electron beam lithography we are able to fabricate side contacts to single nanowires to realize a Hall-measurement geometry. The side contacts allow us to measure a Hall-voltage, from which we deduce the carrier concentration in the wires.

  10. Polymerization of defect states at dislocation cores in InAs

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji-Sang; Yang, Ji-Hui; McMahon, W. E., E-mail: Bill.McMahon@nrel.gov [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Kang, Joongoo [Department of Emerging Materials Science, DGIST, Daegu 711-873 (Korea, Republic of); Wei, Su-Huai, E-mail: suhuaiwei@csrc.ac.cn [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Beijing Computational Science Research Center, Beijing 100094 (China)

    2016-01-28

    Dislocations are essentially lines of point defects which can act as recombination centers in semiconductor devices. These point defects do not behave as isolated defects. Their spatial proximity enables them to hybridize into a one-dimensional band, and the distribution of resulting defect-band states is determined by both the position of the band and its dispersion. In the case of glissile 90° partial dislocations in III-V semiconductors, the dislocation core can adopt a variety of different reconstructions. Each of these reconstructions has a different arrangement of point defects, which affects the hybridization into defect bands and their associated dispersion. Here, we illustrate these principles by performing first-principles calculations for InAs and find that some defect levels for InAs dislocations lie outside of the band gap where they cannot act as recombination centers. To provide some insight into the electronic structure of dislocations in ternary alloys, some examples relevant to InGaAs and GaAsP are included.

  11. An Important Issue: Non-Proliferation of Nuclear Weapons

    Science.gov (United States)

    Castellano, Doc

    2001-03-01

    Historic Facts and Philosophy: In August, 1947, I participated in a secret meeting concerning the validity and use of a hydrogen bomb. I vigorously supported a ``Super Manhattan Project" to build an ``H" bomb. My philosophy at the time was `bigger and better,' to ensure that no nation attacked the U.S. Our retaliation with ``H" bombs vs. ``A" bombs would be too overwhelming for any nation to risk attacking us should they obtain their own ``A" bombs. Thus, all nations would be forced to use diplomacy. I am older and wiser, and am now convinced that World Test Ban Treaties, non-proliferation of nuclear weapons, and space free of any military weapons is the best policy for all nations and humanity. With current nuclear testing at nearby Yucca Flats, Nevada, Vandenberg AF/Missile site, Cal Tech, etc., I therefore propose that our new APS California Division form a three-person committee to tabulate all pertinent data and submit it to a qualified expert for review and further action. Comments and suggestions are invited.

  12. Atoms for peace and the nonproliferation treaty: unintended consequences

    Energy Technology Data Exchange (ETDEWEB)

    Streeper, Charles Blamires [Los Alamos National Laboratory

    2009-01-01

    In April 2009, President Obama revived nonproliferation and arms control efforts with a speech calling for the worldwide abolition of nuclear weapons. His speech correctly acknowledged the threat of nuclear terrorism and the vulnerabilities of the related unsecure nuclear materials. Unfortunately, the president did not mention and has not mentioned in any speech the threat posed by at-risk radiological materials. Nonproliferation efforts have a well documented history of focus on special nuclear materials (fissionable weapons usable materials or SNM), and other key materials (chemical and biological) and technologies for a Weapon of Mass Destruction (WMD). Such intense focus on WMD related materials/technologies is essential for international safety and security and merit continued attention and funding. However, the perception that radioactive sealed sources (sources) are of less concern than WMD is unfortunate. These perceptions are based solely on the potentially enormous and tragic consequences associated with their deliberate or accidental misuse and proliferation concerns. However, there is a documented history of overemphasis on the nuclear threat at the expense of ignoring the far more likely and also devastating chemical and biological threats. The radiological threat should not be minimized or excluded from policy discussions and decisions on these far ranging scopes of threat to the international community. Sources have a long history of use; and a wider distribution worldwide than fissile materials. Pair this with their broad ranges in isotopes/activities along with scant national and international attention and mechanisms for their safe and secure management and it is not difficult to envision a deadly threat. Arguments that minimize or divert attention away from sources may have the effect of distracting necessary policy attention on preventing/mitigating a radiological dispersal event. The terrorist attacks on 9/11 should be a clear reminder of the

  13. Electronic phase coherence in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Bloemers, Christian; Lepsa, Mihail Ion; Lenk, Steffi; Lueth, Hans; Schaepers, Thomas; Gruetzmacher, Detlev [Institute of Bio- and Nanosystems (IBN-1) and JARA - Fundamentals of Future Information Technology, Forschungszentrum Juelich GmbH (Germany)

    2010-07-01

    We report on magnetotransport measurements on InAs nanowires grown by molecular beam epitaxy. Among the III-V semiconductor materials, InAs is particularly interesting because of its low direct band gap and its low effective mass. Additionally InAs is known to show a strong quantum confinement in devices of mesoscopic dimensions. A well known quantum effect revealed by magnetotransport measurements at low temperatures are the universal conductance fluctuations (UCF), resulting from electron interference. By analyzing the UCFs it is possible to draw conclusions about the phase coherence length of the electrons in the device. In the special case of a magnetic field in parallel to the wire, Altshuler-Aronov-Spivak oscillations were found in lithographically defined InAs columns. These oscillations are known to result from the surface 2DEG, which is present in those columns. In contrast the present InAs wires do not show this behavior. The explanation is given in terms of the high density of stacking faults, which were observed in transmission electron microscopy. The stacking faults are due to transitions between wurtzite and zincblende structure. The wurtzite segments are origins of polarization charges which most probably mask the effect of surface states, being the reason for the surface 2DEG.

  14. Development of Computer-Aided Learning Programs on Nuclear Nonproliferation and Control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Chul [Korea Institute of Nuclear Nonproliferation and Control, Daejeon (Korea, Republic of)

    2011-10-15

    The fulfillment of international norms for nuclear nonproliferation is indispensable to the promotion of nuclear energy. The education and training for personnel and mangers related to the nuclear material are one of crucial factors to avoid unintended non-compliance to international norms. Korea Institute of Nuclear Nonproliferation and Control (KINAC) has been providing education and training on nuclear control as its legal duty. One of the legally mandatory educations is 'nuclear control education' performed since 2006 for the observation of the international norms on nuclear nonproliferation and the spread of the nuclear control culture. The other is 'physical protection education' performed since 2010 for maintaining the national physical protection regime effectively and the spread of the nuclear security culture. The 2010 Nuclear Security Summit was held in Washington, DC to enhance international cooperation to prevent nuclear terrorism. During the Summit, the South Korea was chosen to host the second Nuclear Summit in 2012. South Korean President announced that South Korea would share its expertise and support the Summit's mission by setting up an international education and training center on nuclear security in 2014. KINAC is making a full effort to set up the center successfully. An important function of the center is education and training in the subjects of nuclear nonproliferation, nuclear safeguards, nuclear security, and nuclear export/import control. With increasing importance of education and training education on nuclear nonproliferation and control, KINAC has been developing computer-aided learning programs on nuclear nonproliferation and control to overcome the weaknesses in classroom educations. This paper shows two learning programs. One is an e-learning system on the nuclear nonproliferation and control and the other is a virtual reality program for training nuclear material accountancy inspection of light water

  15. Phase coherent transport in hollow InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wenz, T.; Rosien, M.; Haas, F.; Rieger, T.; Lepsa, M. I.; Lüth, H.; Grützmacher, D.; Schäpers, Th., E-mail: th.schaepers@fz-juelich.de [Peter Grünberg Institute (PGI-9) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Demarina, N. [Peter Grünberg Institute (PGI-2) and JARA-Fundamentals of Future Information Technology, Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2014-09-15

    Hollow InAs nanowires are produced from GaAs/InAs core/shell nanowires by wet chemical etching of the GaAs core. At room temperature, the resistivity of several nanowires is measured before and after removal of the GaAs core. The observed change in resistivity is explained by simulating the electronic states in both structures. At cryogenic temperatures, quantum transport in hollow InAs nanowires is studied. Flux periodic conductance oscillations are observed when the magnetic field is oriented parallel to the nanowire axis.

  16. Improved uncertainty quantification in nondestructive assay for nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Burr, Tom; Croft, Stephen; Jarman, Ken; Nicholson, Andrew; Norman, Claude; Walsh, Stephen

    2016-12-01

    This paper illustrates methods to improve uncertainty quantification (UQ) for non-destructive assay (NDA) measurements used in nuclear nonproliferation. First, it is shown that current bottom-up UQ applied to calibration data is not always adequate, for three main reasons: (1) Because there are errors in both the predictors and the response, calibration involves a ratio of random quantities, and calibration data sets in NDA usually consist of only a modest number of samples (3–10); therefore, asymptotic approximations involving quantities needed for UQ such as means and variances are often not sufficiently accurate; (2) Common practice overlooks that calibration implies a partitioning of total error into random and systematic error, and (3) In many NDA applications, test items exhibit non-negligible departures in physical properties from calibration items, so model-based adjustments are used, but item-specific bias remains in some data. Therefore, improved bottom-up UQ using calibration data should predict the typical magnitude of item-specific bias, and the suggestion is to do so by including sources of item-specific bias in synthetic calibration data that is generated using a combination of modeling and real calibration data. Second, for measurements of the same nuclear material item by both the facility operator and international inspectors, current empirical (top-down) UQ is described for estimating operator and inspector systematic and random error variance components. A Bayesian alternative is introduced that easily accommodates constraints on variance components, and is more robust than current top-down methods to the underlying measurement error distributions.

  17. Impact of Monoenergetic Photon Sources on Nonproliferation Applications Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Geddes, Cameron [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ludewigt, Bernhard [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Valentine, John [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Quiter, Brian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Descalle, Marie-Anne [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Warren, Glen [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kinlaw, Matt [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Scott [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chichester, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, Cameron [Univ. of Michigan, Ann Arbor, MI (United States); Pozzi, Sara [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-03-01

    Near-monoenergetic photon sources (MPSs) have the potential to improve sensitivity at greatly reduced dose in existing applications and enable new capabilities in other applications, particularly where passive signatures do not penetrate or are insufficiently accurate. MPS advantages include the ability to select energy, energy spread, flux, and pulse structures to deliver only the photons needed for the application, while suppressing extraneous dose and background. Some MPSs also offer narrow angular divergence photon beams which can target dose and/or mitigate scattering contributions to image contrast degradation. Current bremsstrahlung photon sources (e.g., linacs and betatrons) produce photons over a broad range of energies, thus delivering unnecessary dose that in some cases also interferes with the signature to be detected and/or restricts operations. Current sources must be collimated (reducing flux) to generate narrow divergence beams. While MPSs can in principle resolve these issues, they remain at relatively low TRL status. Candidate MPS technologies for nonproliferation applications are now being developed, each of which has different properties (e.g. broad vs. narrow angular divergence). Within each technology, source parameters trade off against one another (e.g. flux vs. energy spread), representing a large operation space. This report describes a broad survey of potential applications, identification of high priority applications, and detailed simulations addressing those priority applications. Requirements were derived for each application, and analysis and simulations were conducted to define MPS parameters that deliver benefit. The results can inform targeting of MPS development to deliver strong impact relative to current systems.

  18. Crystal structure and transport in merged InAs nanowires MBE grown on (001) InAs.

    Science.gov (United States)

    Kang, Jung-Hyun; Cohen, Yonatan; Ronen, Yuval; Heiblum, Moty; Buczko, Ryszard; Kacman, Perla; Popovitz-Biro, Ronit; Shtrikman, Hadas

    2013-11-13

    Molecular beam epitaxy growth of merging InAs nanowire intersections, that is, a first step toward the realization of a network of such nanowires, is reported. While InAs nanowires play already a leading role in the search for Majorana fermions, a network of these nanowires is expected to promote their exchange and allow for further development of this field. The structural properties of merged InAs nanowire intersections have been investigated using scanning and transmission electron microscope imaging. At the heart of the intersection, a sharp change of the crystal structure from wurtzite to perfect zinc blende is observed. The performed low-temperature conductance measurements demonstrate that the intersection does not impose an obstacle to current transport.

  19. The National Ignition Facility (NIF) and the issue of nonproliferation. Final study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-19

    NIF, the next step proposed by DOE in a progression of Inertial Confinement Fusion (ICF) facilities, is expected to reach the goal of ICF capsule ignition in the laboratory. This report is in response to a request of a Congressman that DOE resolve the question of whether NIF will aid or hinder U.S. nonproliferation efforts. Both technical and policy aspects are addressed, and public participation was part of the decision process. Since the technical proliferation concerns at NIF are manageable and can be made acceptable, and NIF can contribute positively to U.S. arms control and nonproliferation policy goals, it is concluded that NIF supports the nuclear nonproliferation objectives of the United States.

  20. Self-Organized InAs Quantum Wires on GaAs (331)A Substrates

    Institute of Scientific and Technical Information of China (English)

    龚政; 方志丹; 苗振华; 牛智川; 封松林

    2003-01-01

    Self-organized InAs quantum wires (QWRs) were fabricated on the step edges of the GaAs (331)A surface by molecular beam epitaxy. The lateral size of InAs Q WRs was saturated by the terrace width (i.e., 90nm) while the size alongthe step lines increased with the increasing thicknesses of the InAs layers, up to 1100 nm. The height of InAs QWRs varied from 7.9nm to 13nm. The evolution of the morphology of InAs QWRs was attributed to the diffusion anisotropy of In adatoms.

  1. Reconstruction of an InAs nanowire using geometric tomography

    DEFF Research Database (Denmark)

    Pennington, Robert S.; König, Stefan; Alpers, Andreas;

    Geometric tomography and conventional algebraic tomography algorithms are used to reconstruct cross-sections of an InAs nanowire from a tilt series of experimental annular dark-field images. Both algorithms are also applied to a test object to assess what factors affect the reconstruction quality...

  2. Cooperative Remote Monitoring, Arms control and nonproliferation technologies: Fourth quarter 1995

    Energy Technology Data Exchange (ETDEWEB)

    Alonzo, G M [ed.

    1995-01-01

    The DOE`s Cooperative Remote Monitoring programs integrate elements from research and development and implementation to achieve DOE`s objectives in arms control and nonproliferation. The contents of this issue are: cooperative remote monitoring--trends in arms control and nonproliferation; Modular Integrated Monitoring System (MIMS); Authenticated Tracking and Monitoring Systems (ATMS); Tracking and Nuclear Materials by Wide-Area Nuclear Detection (WAND); Cooperative Monitoring Center; the International Remote Monitoring Project; international US and IAEA remote monitoring field trials; Project Dustcloud: monitoring the test stands in Iraq; bilateral remote monitoring: Kurchatov-Argonne-West Demonstration; INSENS Sensor System Project.

  3. A Sustainable WMD Nonproliferation Strategy for East Africa: Connecting the WMD Nonproliferation Agenda with Local Border Security Needs to Achieve Mutually Beneficial Outcomes

    Science.gov (United States)

    2014-01-01

    this light , it is clear that we need a wider discussion on WMD nonproliferation capacity building, which considers the higher priorities of emerging...Administration Police Service, Immigration, Kenya National Focal Point on Small Arms & Light Weapons, National Steering Committee on Peacebuilding & Conflict...consumer goods production, agriculture, horticulture , oil refining, metals, cement, commercial ship repair and tourism. Kenya’s main commodity exports are

  4. 78 FR 9768 - Bureau of International Security and Nonproliferation Imposition of Missile Sanctions on Two...

    Science.gov (United States)

    2013-02-11

    ... of International Security and Nonproliferation Imposition of Missile Sanctions on Two Chinese Foreign.... SUMMARY: A determination has been made that two foreign persons in China have engaged in activities that...) . Accordingly, the following sanctions are being imposed on these foreign persons for two years: (A) Denial of...

  5. Law, Policy and Nonproliferation Project Events and Workshops: Key Themes, Results and Related Materials 2008 - 2009

    Science.gov (United States)

    2010-04-01

    Coast Guard Deborah Berman Monterey Institute James Martin Center for Nonproliferation Studies Chris Bidwell Defense Threat Reduction Agency James...ATTENDEES NAME ORGANIZATION Thomas Appel Booz Allen Hamilton Deborah Berman Monterey Institute for International Studies Chris Bidwell Defense...not credible and that preemptive selfdefense was true ground for action). 108. See generally Harold D. Lasswell & Myres S. McDougal, Jurisprudence

  6. 15 CFR Supplement No. 1 to Part 742 - Nonproliferation of Chemical and Biological Weapons

    Science.gov (United States)

    2010-01-01

    ... Biological Weapons No. Supplement No. 1 to Part 742 Commerce and Foreign Trade Regulations Relating to...—Nonproliferation of Chemical and Biological Weapons Note: Exports and reexports of items in performance of...: (i) Equipment (for producing chemical weapon precursors and chemical warfare agents) described in...

  7. Miscalculated Ambiguity: The Effects of US Nuclear Declaratory Policy on Deterrence and Nonproliferation

    Science.gov (United States)

    2010-06-01

    MIRVs) and anti-ballistic missile ( ABM ) technology began to re-invigorate thinking regarding nuclear warfighting explored under McNamara‘s counter...Nuclear Weapons and Nonproliferation: A Reference Handbook. Contemporary World Issues. ( ABC -CLIO, 2008), 6. policy proved deadly for this initial non

  8. China's Case Against the Nuclear Non-Proliferation Treaty: Rationality and Morality.

    Science.gov (United States)

    Hunt, Geoffrey

    1986-01-01

    China and other major Third World nations have refused to sign the Nuclear Non-Proliferation Treaty (NPT). While this position appears morally unjustified and even irrational, their claim that the treaty is discriminatory merits serious attention. Only if certain aspects of this claim are accepted by the nuclear weapons signatories, does a moral…

  9. Back-end of the fuel cycle and non-proliferation strategies

    Energy Technology Data Exchange (ETDEWEB)

    Chebeskov, A.N.; Oussanov, V.I.; Iougai, S.V.; Pshakin, G.M. [Institute of Physics and Power Engineering, State Scientific Center of Russian Federation, Obninsk (Russian Federation)

    2001-07-01

    The paper focuses on the problem of fissile materials proliferation risk estimation. Some methodological approaches to the solution of this task and results of their application for comparison of different nuclear fuel cycle strategies are discussed. The results of comparative assessment of non-proliferation aspects of plutonium utilization alternatives in Russia using system analysis approach are presented. (author)

  10. The Situation of International Arms Control and Non-proliferation in 2003

    Institute of Scientific and Technical Information of China (English)

    Hou; Hongyu

    2014-01-01

    The international non-proliferation efforts have achieved some positive results. The Iran nuclear issue has taken the first step towards solution; the abolition of Syrian chemical weapon is going ahead according the plan and the UN has adopted the Arms Trade Treaty. However, the DPRK nuclear issue has made no progress yet.

  11. International Relations and HRD Activities of the International Nuclear Nonproliferation and Security Academy of the ROK

    Directory of Open Access Journals (Sweden)

    Kwan Kyoo Choe

    2015-07-01

    Full Text Available The objective of this article is to explain the HRD activities on nuclear nonproliferation and security area of the International Nuclear Nonproliferation and Security Academy (INSA of the Korea Institute of Nuclear Nonproliferation and Control (KINAC. The HRD activities on nuclear security in international society have moved gradually from military dimension to the aspect of social management of conflict and threat. The paper would be developed in the following ways; First, the main concept of nuclear security in the Republic of Korea(ROK will be touched, which could show us why and how the ROK has put its step forward into the HRD efforts. Second, the background in conjunction with international relations and its developing process how the Korea Center of Excellence (COE, named as INSA, had been set would be described. Third, the detailed efforts of the ROK to build a COE in Korea in connection with the 2nd Nuclear Security Summit (NSS will be touched with a detailed explanation on its main activities, direction and the perspective. Finally, the aspect of nuclear culture issues and lessons learned in the first year of the nuclear nonproliferation and security HRD activities of the INSA would be developed.

  12. Fukushima Daiichi: implications for carbon-free energy, nuclear nonproliferation, and community resilience.

    Science.gov (United States)

    Hall, Howard L

    2011-07-01

    Implications of the nuclear power plant accidents at Fukushima Daiichi are explored in this commentary. In addition to questions of nuclear reactor regulatory standards, broader implications on noncarbon-emitting energy production, nuclear nonproliferation objectives, and community resilience and emergency response against catastrophic events are explored. Copyright © 2011 SETAC.

  13. Isolation, Fractionation and Characterization of Catalase from Neurospora crassa (InaCC F226)

    Science.gov (United States)

    Suryani; Ambarsari, L.; Lindawati, E.

    2017-03-01

    Catalase from Indigenous isolate Neurospora crassa InaCC F226 has been isolated, fractionated and characterized. Production of catalase by Neurospora crassa was done by using PDA medium (Potato Dextrosa Agar) and fractionated with ammonium sulphate with 20-80% saturation. Fraction 60% was optimum saturation of ammonium sulphate and had highest specific activity 3339.82 U/mg with purity 6.09 times, total protein 0.920 mg and yield 88.57%. The optimum pH and temperature for catalase activity were at 40°C and pH 7.0, respectively. The metal ions that stimulated catalase activity acted were Ca2+, Mn2+ and Zn2+, and inhibitors were EDTA, Mg2+ and Cu2+. Based on Km and Vmax values were 0.2384 mM and 13.3156 s/mM.

  14. Laser location and manipulation of a single quantum tunneling channel in an InAs quantum dot.

    Science.gov (United States)

    Makarovsky, O; Vdovin, E E; Patané, A; Eaves, L; Makhonin, M N; Tartakovskii, A I; Hopkinson, M

    2012-03-16

    We use a femtowatt focused laser beam to locate and manipulate a single quantum tunneling channel associated with an individual InAs quantum dot within an ensemble of dots. The intensity of the directed laser beam tunes the tunneling current through the targeted dot with an effective optical gain of 10(7) and modifies the curvature of the dot's confining potential and the spatial extent of its ground state electron eigenfunction. These observations are explained by the effect of photocreated hole charges which become bound close to the targeted dot, thus acting as an optically induced gate electrode.

  15. Correlating structure, strain, and morphology of self-assembled InAs quantum dots on GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Kumah, Divine P; Wu, J H; Husseini, Naji S; Dasika, V D; Goldman, Rachel S; Yacoby, Yizhak; Clarke, Roy

    2011-01-01

    We report on the use of a direct x-ray phase retrieval method, coherent Bragg rod analysis, to characterize self-assembled InAs quantum dots (QDs) grown epitaxially on GaAs substrates. Electron density maps obtained close to the x-ray absorption edges of the constituent elements are compared to deconvolute composition and atomic spacing information. Our measurements show no evidence of a wetting layer and reveal bowing of the atomic layers throughout the QD, extending from the QD-substrate interface. This leads to a half-layer stacking shift which may act to partially decouple the QDs electronically from the substrate.

  16. Effect of Annealing on Optical Properties of InAs Quantum Dots Grown by MOCVD on GaAs (100) Vicinal Substrates

    Institute of Scientific and Technical Information of China (English)

    LIANG Song; ZHU Hong-Liang; PAN Jiao-Qing; ZHAO Ling-Juan; WANG Wei

    2005-01-01

    @@ Thermal annealing effect on InAs quantum dots grown on vicinal (100) GaAs substrates is studied in comparison with dots on exact (100) GaAs substrates. We find that annealing acts stronger effect on dots with vicinal substrates by greatly accelerating the degradation of material quality, as well as slightly increasing the blueshift of the emission wavelength and the narrowing of PL linewidth. It is attributed to the higher strain in the dots formed on the vicinal substrates.

  17. Structural influences on quantum transport in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Frielinghaus, Robert; Sladek, Kamil; Trellenkamp, Stefan; Hardtdegen, Hilde; Schneider, Claus M.; Meyer, Carola [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany); Floehr, Kilian [II. Physikalisches Institut, RWTH Aachen University, 52074 Aachen (Germany); JARA - Fundamentals of Future Information Technology (Germany); Weirich, Thomas E. [Central Facility for Electron Microscopy GFE, RWTH Aachen University, 52074 Aachen (Germany); JARA - Fundamentals of Future Information Technology (Germany); Schaepers, Thomas [Peter Gruenberg Institut, Forschungszentrum Juelich (Germany); II. Physikalisches Institut, RWTH Aachen University, 52074 Aachen (Germany); JARA - Fundamentals of Future Information Technology (Germany)

    2012-07-01

    Self-assembled nanostructures such as InAs nanowires are candidates for future semiconductor nanoscale devices. However their atomic arrangement usually differs from device to device leading to fluctuations in the electrical properties as e.g. the electron phase coherence length. Using a special sample design we present quantum transport measurements together with transmission electron micrographs (TEM) taken from the same individual InAs nanowires. The as-grown nanowires are selectively placed on holes patterned in a TEM membrane. Low-temperature magnetotransport measurements of these suspended nanowires reveal universal conductance fluctuations that allow for the determination of the phase coherence length without any influence of the substrate. Variations in the transport behavior are correlated to the atomically resolved structure observed in TEM.

  18. InAs based terahertz quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Brandstetter, Martin, E-mail: martin.brandstetter@tuwien.ac.at; Kainz, Martin A.; Krall, Michael; Schönhuber, Sebastian; Unterrainer, Karl [Photonics Institute and Center for Micro- and Nanostructures, Technische Universität Wien, Gusshausstrasse 27-29, 1040 Vienna (Austria); Zederbauer, Tobias; Schrenk, Werner; Andrews, Aaron Maxwell; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Technische Universität Wien, Floragasse 7, 1040 Vienna (Austria); Detz, Hermann [Austrian Academy of Sciences, Dr. Ignaz Seipel-Platz 2, 1010 Vienna (Austria)

    2016-01-04

    We demonstrate terahertz lasing emission from a quantum cascade structure, realized with InAs/AlAs{sub 0.16}Sb{sub 0.84} heterostructures. Due to the lower effective electron mass, InAs based active regions are expected to provide a higher optical gain compared to structures consisting of GaAs or InGaAs. The growth by molecular beam epitaxy enabled the fabrication of monolayer-thick barriers, required for the active region, which is based on a 3-well resonant phonon depletion design. Devices were processed in a double-metal waveguide geometry to ensure high mode confinement and low optical losses. Lasing emission at 3.8 THz was observed at liquid helium temperatures by applying a magnetic field perpendicular to the layered structure in order to suppress parasitic scattering channels. These results demonstrate the feasibility of InAs based active regions for terahertz quantum cascade lasers, potentially enabling higher operating temperatures.

  19. 22 CFR 40.68 - Aliens subject to INA 222(g).

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Aliens subject to INA 222(g). 40.68 Section 40... § 40.68 Aliens subject to INA 222(g). An alien who, under the provisions of INA 222(g), has voided a... new nonimmigrant visa unless the alien complies with the requirements in 22 CFR 41.101 (b) or (c...

  20. Iran's Relations to the East: Nonproliferation and Regional Security in a Changing Southwest Asia

    Energy Technology Data Exchange (ETDEWEB)

    Tehsin, Muhammad [Quaid-I-Azam Univ., Islamabad (Pakistan)

    2014-11-01

    This study attempts to answer the following questions: would a successful JPOA result in nuclear nonproliferation and regional security in Southwest Asia; and could the Middle East and South Asia work together to contain the threat of Salafi jihadism?

  1. NNSA Nonproliferation Graduate Fellowship Program Annual Report June 2008 - May 2009

    Energy Technology Data Exchange (ETDEWEB)

    Berkman, Clarissa O.; Fankhauser, Jana G.

    2010-03-01

    In 2009, the Nonproliferation Graduate Fellowship Program (NGFP) completed its 16th successful year in support of the NNSA’s mission by developing future leaders in nonproliferation and promoting awareness of career opportunities. We provide this annual report to review program activities from June 2008 through May 2009 - the fellowship term for the Class of 2008. Contents include: Welcome Letter Introduction The NGFP Team Program Management Highlights Class of 2008 Incoming Fellows Orientation Travel Career Development Management of the Fellows Performance Highlights Closing Ceremony Encore Performance Where They Are Now Alumnus Career Highlights: Christine Buzzard Class of 2009 Applicant Database Upgrades Fall Recruitment Activities Interviews Hiring and Clearances Introducing the Class of 2009 Class of 2010 Recruitment Strategy On the Horizon Appendix A: Class of 2009 Fellows

  2. NNSA Nonproliferation Graduate Fellowship Program Annual Report June 2009 - May 2010

    Energy Technology Data Exchange (ETDEWEB)

    Berkman, Clarissa O.; Fankhauser, Jana G.

    2011-04-01

    In 2009, the Nonproliferation Graduate Fellowship Program (NGFP) completed its 17th successful year in support of the NNSA’s mission by developing future leaders in nonproliferation and promoting awareness of career opportunities. This annual report to reviews program activities from June 2009 through May 2010 - the fellowship term for the Class of 2009. Contents include: Welcome Letter (Mission Driven: It’s all about results), Introduction, Structure of the NGFP, Program Management Highlights, Annual Lifecycle, Class of 2009 Incoming Fellows, Orientation, Global Support of the Mission, Career Development, Management of the Fellows, Performance Highlights, Closing Ceremony, Where They Are Now, Alumni Highlight - Mission Success: Exceptional Leaders from the NGFP, Class of 2009 Fall Recruitment Activities, Established Partnerships, Face-to-Face, Recruiting Results, Interviews, Hiring and Clearances, Introducing the Class of 2010, Class of 2011 Recruitment Strategy, On the Horizon, Appendix A: Class of 2010 Fellow Biographies

  3. The Physics and Nuclear Nonproliferation Goals of WATCHMAN: A WAter CHerenkov Monitor for ANtineutrinos

    CERN Document Server

    Askins, M; Bernstein, A; Dazeley, S; Dye, S T; Handler, T; Hatzikoutelis, A; Hellfeld, D; Jaffke, P; Kamyshkov, Y; Land, B J; Learned, J G; Marleau, P; Mauger, C; Gann, G D Orebi; Roecker, C; Rountree, S D; Shokair, T M; Smy, M B; Svoboda, R; Sweany, M; Vagins, M R; van Bibber, K A; Vogelaar, R B; Wetstein, M J; Yeh, M

    2015-01-01

    This article describes the physics and nonproliferation goals of WATCHMAN, the WAter Cherenkov Monitor for ANtineutrinos. The baseline WATCHMAN design is a kiloton scale gadolinium-doped (Gd) light water Cherenkov detector, placed 13 kilometers from a civil nuclear reactor in the United States. In its first deployment phase, WATCHMAN will be used to remotely detect a change in the operational status of the reactor, providing a first- ever demonstration of the potential of large Gd-doped water detectors for remote reactor monitoring for future international nuclear nonproliferation applications. During its first phase, the detector will provide a critical large-scale test of the ability to tag neutrons and thus distinguish low energy electron neutrinos and antineutrinos. This would make WATCHMAN the only detector capable of providing both direction and flavor identification of supernova neutrinos. It would also be the third largest supernova detector, and the largest underground in the western hemisphere. In a...

  4. Problems of the nuclear non-proliferation policy. Probleme der nuklearen Nichtverbreitungspolitik; Beitraege zur internationalen Diskussion

    Energy Technology Data Exchange (ETDEWEB)

    Blix, H.; Butler, P. von; Fischer, W.; Caccia Dominioni, F.; Frick, H.; Gmelin, W.; Haeckel, E.; Lauppe, W.D.; Mueller, H.; Richter, B.; Stein, G.

    1994-05-01

    The volume assembles a number of essays wherein basic problems of nonproliferation are identified and discussed in view of recent developments and future policy requirements. What is the role of multilateral institutions in the containment of nuclear proliferation How are Western Europe's security needs to be reconciled with the tenets of the global nonproliferation regime How can international safeguards be upgraded so as to increase confidence among states What kinds of disciplinary instruments are needed for the international community to prevent an unco-operative state from gaining access to nuclear weapons What kinds of obstacles stand in the way of smooth co-operation between the European Union and the United States in the nuclear field How does the demise of global bipolarity impinge on the need to pursue an international nuclear order The essays in this volume seek to combine structural analysis of conceptual issues with substantive policy recommendations. (orig./HP)

  5. Framework for Proliferation Resistance and Physical Protection for Nonproliferation Impact Assessments.

    Energy Technology Data Exchange (ETDEWEB)

    Bari,R.

    2008-03-01

    This report describes a framework for proliferation resistance and physical protection evaluation for the fuel cycle systems envisioned in the expansion of nuclear power for electricity generation. The methodology is based on an approach developed as part of the Generation IV technical evaluation framework and on a qualitative evaluation approach to policy factors similar to those that were introduced in previous Nonproliferation Impact Assessments performed by DOE.

  6. Preparation for the Nuclear Non-Proliferation Treaty Extension Conference in 1995. Workshop summary

    Energy Technology Data Exchange (ETDEWEB)

    Chrzanowski, P.L.

    1993-05-07

    About 30 specialists in non-proliferation participated in a workshop to explore ideas for US Government preparatory steps leading to the 1995 Nuclear Non-Proliferation Treaty (NPT) Extension Conference. To that end, workshop sessions were devoted to reviewing the lessons learned from previous Review Conferences, discussing the threats to the non-proliferation regime together with ways of preserving and strengthening it, and examining the management of international nuclear commerce. A fundamental premise shared by workshop participants was that extension of the NPT is immensely important to international security. The importance of stemming proliferation and, more specifically, extending the Treaty, is growing as a result of the significant changes in the world. If the conferees of the Extension Conference decide on no extension or extension for a short limited duration, some technically advanced states that have foregone development of nuclear weapons may begin to rethink their options. Also, other arms control measures, such as the Chemical Weapons Convention, could start to unravel. The US must provide strong international leadership to ensure that the Extension Conference is a success, resulting in Treaty extension, perhaps through successive terms, into the indefinite future. Workshop participants were struck by the urgent need for the US to take organizational steps so that it is highly effective in its advance preparations for the Extension Conference. Moreover, the Extension Conference provides both a challenge and an opportunity to mold a cohesive set of US policy actions to define the future role of nuclear weapons and combat their proliferation.

  7. NSAIDs induce apoptosis in nonproliferating ovarian cancer cells and inhibit tumor growth in vivo.

    Science.gov (United States)

    Duncan, Kristal; Uwimpuhwe, Henriette; Czibere, Akos; Sarkar, Devanand; Libermann, Towia A; Fisher, Paul B; Zerbini, Luiz F

    2012-07-01

    Ovarian cancer (OC) is one of the most lethal gynaecological cancers, which usually has a poor prognosis due to late diagnosis. A large percentage of the OC cell population is in a nonproliferating and quiescent stage, which poses a barrier to success when using most chemotherapeutic agents. Recent studies have shown that several nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in the treatment of OC. Furthermore, we have previously described the molecular mechanisms of NSAIDs' induction of cancer apoptosis. In this report, we evaluated various structurally distinct NSAIDs for their efficacies in inducing apoptosis in nonproliferating OC cells. Although several NSAIDs-induced apoptosis, Flufenamic Acid, Flurbiprofen, Finasteride, Celocoxib, and Ibuprofen were the most potent NSAIDs inducing apoptosis. A combination of these agents resulted in an enhanced effect. Furthermore, we demonstrate that the combination of Flurbiprofen, which targets nonproliferative cells, and Sulindac Sulfide, that affects proliferative cells, strongly reduced tumor growth when compared with a single agent treatment. Our data strongly support the hypothesis that drug treatment regimens that target nonproliferating and proliferating cells may have significant efficacy against OC. These results also provide a rationale for employing compounds or even chemically modified NSAIDs, which selectively and efficiently induce apoptosis in cells during different stages of the cell cycle, to design more potent anticancer drugs.

  8. Switching current distributions in InAs nanowire Josephson junctions

    Science.gov (United States)

    Kim, Bum-Kyu; Doh, Yong-Joo

    2016-08-01

    We report on the switching current distributions in nano-hybrid Josephson junctions made of InAs semiconductor nanowires. The temperature dependence of the switching current distribution can be understood through the motion of Josephson phase particles escaping from a tilted washboard potential, and the data could be fitted well by using the macroscopic quantum tunneling, thermal activation or phase diffusion models, depending on temperature. Application of the gate voltage to tune the Josephson coupling strength enable us to adjust the effective temperature for the escape process, and holds promising for developing gate-tunable superconducting phase qubits.

  9. Elastic properties and electron transport in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Migunov, Vadim

    2013-02-22

    The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It

  10. 20 CFR 668.650 - Can INA grantees exclude segments of the eligible population?

    Science.gov (United States)

    2010-04-01

    ... eligible population? 668.650 Section 668.650 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION... population? (a) No, INA grantees cannot exclude segments of the eligible population. INA grantees must document in their Two Year Plan that a system is in place to afford all members of the eligible population...

  11. Finland and nuclear non-proliferation: The evolution and cultivation of a norm

    Energy Technology Data Exchange (ETDEWEB)

    Dassen, L. van [Uppsala Univ. (Sweden). Dept. of Peace and Conflict Research

    1998-03-01

    Finland``s entrance on the non-proliferation scene was in 1963 when President Kekkonen suggested a Nordic nuclear-weapons-free zone (NWFZ). This started a debate in and among the Nordic countries and it created a Finnish profile towards the Soviet Union. In most cases, the Soviets tried to bring Finland into a much closer relationship with the USSR. The mere prospect and debate on a Nordic NWFZ reduced the incentive for the Soviets to undermine Finnish neutrality or their desire to suggest consultations according to the Treaty of Friendship, Cooperation and Mutual Assistance on military assistance in the case of a threat to Soviet and/or Finnish security. During the negotiations on the Non-Proliferation Treaty, 1965-1968, Finland played a very active role as a bridge-builder, first between the superpowers and later between the developed and the developing world. This activity gave Finland a name in the UN, strengthened its neutrality and established good relations with the West as well. In 1978, Kekkonen brought up the Nordic NWFZ once more, this time under influence of certain strategic challenges to Finland and general East-West developments. In this Kekkonen had much backing by the public in Finland whereas other states reacted very reluctantly. Politics in Finland has to a large extent been marked by the relations with Russia and later the Soviet Union. However, nuclear non-proliferation was used to ease the weight of this imposing neighbour; a strategy that certainly must be regarded as successful. While achieving this, it was also possible to increase contacts with western states and remain accepted as a neutral state. For Finland, non-proliferation policy was initially a suitable issue to solve other problems than those related exclusively to proliferation. But it was also a policy with a high degree of persistence, pragmatism and willingness to work with concrete issues that maybe do not reach the international limelight in the short run but that work in

  12. Swedish support programme on nuclear non-proliferation in Central and Eastern Europe and Central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Ek, P.; Andersson, Sarmite [Swedish Nuclear Power Inspectorate, Stockholm (Sweden); Wredberg, L. [ILG Consultant Ltd., Vienna (Austria)

    2000-06-15

    At the request of the Swedish Government, the Swedish Nuclear Power Inspectorate has established a support and co-operation programme in the area of nuclear non-proliferation with Russia and several of the republics of the former Soviet Union. The Programme was initiated in 1991 and an overall goal is to accomplish national means and measures for control and protection of nuclear material and facilities, in order to minimise the risk of proliferation of nuclear weapons and illicit trafficking of nuclear material and equipment. The objective of the Swedish Support Programme is to help each, so called, recipient State to be able to, independently and without help from outside, take the full responsibility for operating a national non-proliferation system and thereby fulfil the requirements imposed through the international legal instruments. This would include both the development and implementation of a modern nuclear legislation system, and the establishment of the components making up a national system for combating illicit trafficking. The support and co-operation projects are organised in five Project Groups (i.e. nuclear legislation, nuclear material control, physical protection, export/import control, and combating of illicit trafficking), which together cover the entire non-proliferation area. Up till June 2000, support and co-operation projects, completed and on-going, have been carried out in ten States, namely Armenia, Azerbaijan, Belarus, Georgia, Kazakstan, Latvia, Lithuania, Moldova, Russia and Ukraine. Furthermore, programmes have been initiated during the first part of 2000 with Estonia, Uzbekistan, Kyrgyzstan and Tajikistan. In addition, assistance has been given to Poland on a specific nuclear material accountancy topic. All projects are done on request by and in co-operation with these States. The total number of projects initiated during the period 1991 to June 2000 is 109, thereof 77 have been completed and 32 are currently on-going. It is the

  13. Modulation Spectroscopy of GaAs Covered by InAs Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    金鹏; 孟宪权; 张子旸; 李成明; 曲胜春; 徐波; 刘峰奇; 王占国; 李乙钢; 张存洲; 潘士宏

    2002-01-01

    Contactless electroreflectance has been employed at room temperature to study the Fermi level pinning atundoped-n+ GaAs surfaces covered by 1.6 and 1.8 monolayer (ML) InAs quantum dots (QDs). It is shownthat the 1.8 ML InAs QD moves the Fermi level at GaAs surface to the valence band maximum by about 70 meVcompared to bare GaAs, whereas 1.6 ML InAs on GaAs does not modify the Fermi level. It is corzfirmed thatthe modiffication of the 1.8 ML InAs deposition on the Fermi level at GaAs surface is due to the QDs, which aresurrounded by some oxidized InAs facets, rather than the wetting layer.

  14. Late sodium current (INaL) in pancreatic β-cells.

    Science.gov (United States)

    Rizzetto, Riccardo; Rocchetti, Marcella; Sala, Luca; Ronchi, Carlotta; Villa, Alice; Ferrandi, Mara; Molinari, Isabella; Bertuzzi, Federico; Zaza, Antonio

    2015-08-01

    Recent evidence of beneficial effects of ranolazine (RAN) in type II diabetes motivates interest in the role of the late sodium current (INaL) in glucose-stimulated insulin secretion. In the present work, we characterize INaL and its function in rat INS-1E cells and human islets cells. INaL was identified as steady-state current blocked by 10 μM RAN (IRAN) or 0.5 μM tetrodotoxin (TTX) (ITTX). Veratridine (VERA, 40 μM) was used as INaL enhancer. Baseline INaL was similar between INS-1E and human islet cells. In INS-1E cells, activated by glucose or tolbutamide, TTX or RAN hyperpolarized membrane potential (V m). VERA-induced depolarization was countered by TTX or RAN. ITTX and IRAN reversal potentials were negative to Na(+) equilibrium one, but they approached it after Na(+) substitution with Li(+) or when K(+) channels were blocked. This revealed INaL coupling with Na(+)-activated K(+) current (IKNa); expression of IKNa channels (Slick/Slack) was confirmed by transcript analysis and Western blot. RAN or TTX blunted cytosolic Ca(2+) response to depolarization. Long-term incubation in high (33 mM) glucose (CHG) constitutively enhanced INaL. VERA immediately increased glucose-stimulated insulin secretion. CHG increased glucose-independent secretion instead and abolished the secretory response to glucose. RAN or TTX countered VERA- and CHG-induced changes in insulin secretion. Our study demonstrated that (1) INaL was expressed in insulin-secreting cells and coupled to IKNa; INaL affected cytosolic Ca(2+) but, unless enhanced, barely contributed to glucose-stimulated insulin secretion (GSIS); and (2) sustained hyperglycemic stress enhanced INaL, which contributed to the attending increase of glucose-independent insulin "leak" and GSIS impairment.

  15. DC measurements on InAs two-stage spin-filter cascades

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Jan; Lehmann, Hauke; Bisotti, Marc-Antonio; Matsuyama, Toru; Meier, Guido; Merkt, Ulrich [Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Universitaet Hamburg (Germany)

    2010-07-01

    For spintronics it is a prerequisite to create devices capable of generating and detecting spin-polarized currents. We present an all-semiconductor nanostructure based on an InAs heterostructure, which can be used to generate spin-polarized currents all-electrically utilizing the intrinsic spin Hall effect in a Y-shaped junction. By cascading two spin filters the first acts as a generator of spin-polarized currents while the second acts as an all-electrical detector. Measurements applying an AC voltage to the two-stage spin-filter cascade have proven the feasibility of these devices as efficient generators and detectors for spin-polarized currents. For the investigation of the influence of magnetic and electric fields in different directions it is essential to use DC voltages to direct the electron flow in constant direction instead of alternating directions in the AC case and thereby keeping the geometric relation between the current flow and the applied field constant. To enable lock-in technique we apply a DC voltage with AC modulation to the spin-filter cascade.

  16. Geometry dependent transport properties of undoped InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Guenel, H. Yusuf; Bloemers, Christian; Sladek, Kamil; Penz, Andreas; Hardtdegen, Hilde; Lenk, Steffi; Schubert, Juergen; Schaepers, Thomas; Gruetzmacher, Detlev [Institute of Bio- and Nanosystems (IBN-1) and JARA-Fundamentals of Future Information Technology, Research Centre Juelich GmbH, 52425 Juelich (Germany); Luysberg, Martina [Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forchungszentrum Juelich, 52425 Juelich (Germany)

    2010-07-01

    In recent time nanowire (NW) structures attracted much attention, for electronics, optoelectronics and fundamental quantum properties. On account of different application purposes basic transport properties are crucially important at room temperature as well as low temperatures. In this respect InAs NWs are particularly important due to the low band gap and high carrier concentration. We characterized the basic transport parameters of undoped InAs NWs at room temperature, which were grown on GaAs(001) substrate by MOVPE without catalyst. The NWs that we used in this work had diameters ranging from 25 nm to 200 nm and lengths up to 3.5 {mu}m. Basic transport parameters, such as carrier concentration and mobility, were determined by using two- and four-terminal measurement configuration. The carrier concentration could be controlled by a SiO{sub 2} -isolated back-gate structure. By analyzing the transfer characteristics of the NW FET, we observed very good gate controllability.

  17. Ballistic modeling of InAs nanowire transistors

    Science.gov (United States)

    Jansson, Kristofer; Lind, Erik; Wernersson, Lars-Erik

    2016-01-01

    In this work, the intrinsic performance of InAs nanowire transistors is evaluated in the ballistic limit. A self-consistent Schrödinger-Poisson solver is utilized in the cylindrical geometry, while accounting for conduction band non-parabolicity. The transistor characteristics are derived from simulations of ballistic transport within the nanowire. Using this approach, the performance is calculated for a continuous range of nanowire diameters and the transport properties are mapped. A transconductance exceeding 4S /mm is predicted at a gate overdrive of 0.5V and it is shown that the performance is improved with scaling. Furthermore, the influence from including self-consistency and non-parabolicity in the band structure simulations is quantified. It is demonstrated that the effective mass approximation underestimates the transistor performance due to the highly non-parabolic conduction band in InAs. Neglecting self-consistency severely overestimates the device performance, especially for thick nanowires. The error introduced by both of these approximations gets increasingly worse under high bias conditions.

  18. 77 FR 49821 - Exercise of Authority Under the Immigration and Nationality Act

    Science.gov (United States)

    2012-08-17

    ... SECURITY Office of the Secretary Exercise of Authority Under the Immigration and Nationality Act AGENCY... Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as well as the foreign policy... Refugee Immigration Fairness Act (HRIFA), or granted a similar immigration benefit other than a...

  19. Study of growth properties of InAs islands on patterned InP substrates defined by focused ion beam

    Science.gov (United States)

    Ribeiro-Andrade, R.; Malachias, A.; Miquita, D. R.; Vasconcelos, T. L.; Kawabata, R.; Pires, M. P.; Souza, P. L.; Rodrigues, W. N.

    2017-03-01

    This work describes morphological and crystalline properties of the InAs islands grown on templates created by focused ion beam (FIB) on indium phosphide (InP) substrates. Regular arrangements of shallow holes are created on the InP (001) surfaces, acting as preferential nucleation sites for InAs islands grown by Metal-Organic Vapor Phase Epitaxy. Ion doses ranging from 1015 to 1016 Ga+/cm2 were used and islands were grown for two sub-monolayer coverages. We observe the formation of clusters in the inner surfaces of the FIB produced cavities and show that for low doses templates the nanostructures are mainly coherent while templates created with large ion doses lead to the growth of incoherent islands with larger island density. The modified island growth is described by a simple model based on the surface potential and the net adatom flow to the cavities. We observe that obtained morphologies result from a competition between coarsening and coalescence mechanisms.

  20. Progress in low light-level InAs detectors- towards Geiger-mode detection

    Science.gov (United States)

    Tan, Chee Hing; Ng, Jo Shien; Zhou, Xinxin; David, John; Zhang, Shiyong; Krysa, Andrey

    2017-05-01

    InAs avalanche photodiodes (APDs) can be designed such that only electrons are allowed to initiate impact ionization, leading to the lowest possible excess noise factor. Optimization of wet chemical etching and surface passivation produced mesa APDs with bulk dominated dark current and responsivity that are comparable and higher, respectively, than a commercial InAs detector. Our InAs electron-APDs also show high stability with fluctuation of 0.1% when operated at a gain of 11.2 over 60 s. These InAs APDs can detect very weak signal down to 35 photons per pulse. Fabrication of planar InAs by Be implantation produced planar APDs with bulk dominated dark current. Annealing at 550 °C was necessary to remove implantation damage and to activate Be dopants. Due to minimal diffusion of Be, thick depletion of 8 μm was achieved. Since the avalanche gain increases exponentially with the thickness of avalanche region, our planar APD achieved high gain > 300 at 200 K. Our work suggest that both mesa and planar InAs APDs can exhibit high gain. When combined with a suitable preamplifier, single photon detection using InAs electron-APDs could be achieved.

  1. INa and IKir are reduced in Type 1 hypokalemic and thyrotoxic periodic paralysis.

    Science.gov (United States)

    Puwanant, Araya; Ruff, Robert L

    2010-09-01

    We evaluated voltage-gated Na(+) (I(Na)) and inward rectifier K(+) (I(Kir)) currents and Na(+) conductance (G(Na)) in patients with Type 1 hypokalemic (HOPP) and thyrotoxic periodic paralysis (TPP). We studied intercostal muscle fibers from five subjects with HOPP and one with TPP. TPP was studied when the patient was thyrotoxic (T-toxic) and euthyroid. We measured: (1) I(Kir), (2) action potential thresholds, (3) I(Na), (4) G(Na), (5) intracellular [Ca(2+)], and (6) histochemical fiber type. HOPP fibers had lower I(Na), G(Na), and I(Kir) and increased action potential thresholds. Paralytic attack frequency correlated with the action potential threshold, G(Na) and I(Na), but not with I(Kir). G(Na), I(Na), and [Ca(2+)] varied with fiber type. HOPP fibers had increased [Ca(2+)]. The subject with TPP had values for G(Na), I(Na), action potential threshold, I(Kir), and [Ca(2+)] that were similar to HOPP when T-toxic and to controls when euthyroid. HOPP T-toxic TPP fibers had altered G(Na), I(Na), and I(Kir) associated with elevation in [Ca(2+)].

  2. Sweden and the making of nuclear non-proliferation: from indecision to assertiveness

    Energy Technology Data Exchange (ETDEWEB)

    Dassen, L. van [Uppsala Univ. (Sweden). Dept. of Peace and Conflict Research

    1998-03-01

    Swedish research on nuclear weapons started at a modest scale in 1945 but was soon expanded. By the early 1950s the research programme started to face some of the problems that were going to accompany it for the rest of its life: different priorities and cost-estimates were made by the sectors that wanted to develop nuclear energy and those working on the bomb. Moreover, an introduction of nuclear weapons would lead to a major redistribution of resources to the disadvantage of the navy and army. The public and political debates intensified during the 1950s and culminated in 1960. At first, pro-nuclear voices had been strongest but were soon challenged by interest groups, unions and peace movements. 1960, a committee within the government had established a compromise: Nuclear weapons research for production of weapons would be terminated, while research on the consequences of nuclear weapons would continue. It was a cosmetic decision that could cover for a continued research on weapons design. Nevertheless, there are some general qualities from the debates that indicate why the outcome was that Sweden signed the NPT in 1968. First, the number of interested persons, groups movements and party politicians engaged in the issue increased every time the issue came up. Secondly, the segments of society that supported the nuclear option remained roughly the same. No strong movements rallied to the defence of this position. On the other hand, the anti-nuclear wing received more and more followers. Third, there was a marked tendency by virtually all actors (except the military) to include every sign of progress in international disarmament and non-proliferation efforts as arguments against Swedish proliferation. Since 1968, the non-proliferation choice has ben manifested through Sweden``s adherence to the NPT and this has been accompanied by a strong commitment to other non-proliferation initiatives. Refs.

  3. Leo Szilard Lectureship Award: Science Matters - Technical Dimensions of Arms Control and Non-Proliferation Agreements

    Science.gov (United States)

    Timbie, James

    2017-01-01

    Agreements to reduce nuclear arms and prevent proliferation of nuclear weapons are technical as well as political documents. They must be both technically sound and politically acceptable. This presentation illustrates technical aspects of arms control and non-proliferation agreements, with examples from SALT I, INF, the HEU Agreement, START, and the Iran nuclear negotiations, drawing on 44 years of personal experience in the negotiation of these agreements. The lecture is designed to convey an appreciation of the role that individuals with technical training can play in diplomatic efforts to reduce nuclear forces and prevent nuclear proliferation.

  4. Selected Examples of LDRD Projects Supporting Test Ban Treaty Verification and Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Al-Ayat, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Walter, W. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-02-23

    The Laboratory Directed Research and Development (LDRD) Program at the DOE National Laboratories was established to ensure the scientific and technical vitality of these institutions and to enhance the their ability to respond to evolving missions and anticipate national needs. LDRD allows the Laboratory directors to invest a percentage of their total annual budget in cutting-edge research and development projects within their mission areas. We highlight a selected set of LDRD-funded projects, in chronological order, that have helped provide capabilities, people and infrastructure that contributed greatly to our ability to respond to technical challenges in support of test ban treaty verification and nonproliferation.

  5. Predicting linear and nonlinear time series with applications in nuclear safeguards and nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Burr, T.L.

    1994-04-01

    This report is a primer on the analysis of both linear and nonlinear time series with applications in nuclear safeguards and nonproliferation. We analyze eight simulated and two real time series using both linear and nonlinear modeling techniques. The theoretical treatment is brief but references to pertinent theory are provided. Forecasting is our main goal. However, because our most common approach is to fit models to the data, we also emphasize checking model adequacy by analyzing forecast errors for serial correlation or nonconstant variance.

  6. Predicting linear and nonlinear time series with applications in nuclear safeguards and nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Burr, T.L.

    1994-04-01

    This report is a primer on the analysis of both linear and nonlinear time series with applications in nuclear safeguards and nonproliferation. We analyze eight simulated and two real time series using both linear and nonlinear modeling techniques. The theoretical treatment is brief but references to pertinent theory are provided. Forecasting is our main goal. However, because our most common approach is to fit models to the data, we also emphasize checking model adequacy by analyzing forecast errors for serial correlation or nonconstant variance.

  7. Increasing Inspectability of Hardware and Software for Arms Control and Nonproliferation Regimes

    Energy Technology Data Exchange (ETDEWEB)

    White, G

    2001-07-18

    As the U.S. and the Russian Federation get closer to deploying systems for monitoring nuclear material within arms control and nonproliferation transparency regimes, the level of inspectability of the system hardware and software must increase beyond the systems demonstrated to date. These systems include the Trilateral Initiative prototype, the Fissile Material Transparency Technology Demonstration (FMTTD) system, and the Trusted Radiation Attribute Demonstration System (TRADS). Toward this goal, several alternative technologies will be discussed along with ways in which they would increase inspectability. Some examples of such technologies include the use of microcontrollers instead of fully capable computers, open source operating systems, rantime environments, and compilers.

  8. Post-Cold War Effects on the Non-proliferation Regime

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, Carol E.

    2006-03-31

    This journal article analyzes nuclear and security related events of the past 15 years to illustrate the changes in geopolitics and the shifting balance of power following the collapse of the Soviet Union. Reflection upon these events establishes the context for strengthening the nonproliferation regime. The author concludes that post Soviet communism hastened the movement towards a unipolar system with hegemonic power vested in the United States, and this geopolitical imbalance fostered insecurities and greater threats. Multilateral cooperation and commitment from the US would help this leader achieve its goal of security through increased global confidence in the international system.

  9. Anomalous damage in N sup + implanted InAs

    Energy Technology Data Exchange (ETDEWEB)

    Aydinli, A.; Drigo, A.V. (Padua Univ. (Italy). Ist. di Fisica)

    1990-01-01

    Damage production in (100)InAs by room temperature implantation of N{sup +} at 50 keV in the range of 1E15 to 2E17 N{sup +}/cm{sup 2} has been studied by RBS/Channeling. The {sup 14}N(d,p){sup 15}N nuclear reaction was used to check the implanted doses. A quasi saturation of damage at 2E16 N{sup +}/cm{sup 2} was followed by apparent amorphization of the surface at {approx} 1E17 N{sup +}/cm{sup 2}. Channeling measurements at different probe energies have shown that the damage at the highest dose consists of both point and extended defects with small regions of local order still remaining in the matrix. (author).

  10. COMPLEX LANDSLIDE IN THE RJEČINA RIVER VALLEY

    Directory of Open Access Journals (Sweden)

    Čedomir Benac

    1999-12-01

    Full Text Available This paper presents the first phase investigation results of the complex landslide situated on north-eastern slope of the Rječina valley, between Valići damm and the village of Pašac. The valley slopes were formed in Paleogene flysch and Quaternary formations. The limestone rocks are present on the top sites, forming the scarps there. The complex landslide formation has been preconditioned by the geological structure and morphogenesis of the Rječina valley. This is the type of complex retrogressive landslide, starting with its development from toe to head. Thirteen individual landslide bodies were discovered on the slope. The material of slope formation and a part of weathering zone is caught by the landsliding. The larger part of landslide body is saturated by underground water penetrating through the covering zone in contact with flysch bedrock. The landsliding is relatively shallow, because there is no visible damage affected by sliding in the hydrotechnical tunnel, situated below the landslide toe. The mega-blocks of the limestone rock have also been moved and, most probably, are sliding down the flysch bedrock. This is a special phenomenon, atypical of the flysch slope landslide type in the area of Rijeka. The limestone rock on a scarp is extremely disintegrated, with new visible fractures in it. The site investigations comprised the surveying, seismic and engineering geological explorations. The surveying was performed by the method of terrestrial photogrammetry. The results are compared with aerial photos from 1981. In this respect, it was possible to discover the changes of slope morphology during the period 1981 — 1997. The photos were also used for the engineering geological mapping supplementation. The seismic surveying was performed by the surface seismic refraction method (the paper is published in Croatian.

  11. Nuclear proliferation and civilian nuclear power: report of the Nonproliferation Alternative Systems Assessment Program. Volume VII. International perspectives

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-12-01

    The purpose of this volume is to assess the proliferation vulnerabilities of the present deployment of civilian nuclear-power systems within the current nonproliferation regime and, in light of their prospective deployment, to consider technical and institutional measures and alternatives which may contribute to an improved regime in which nuclear power could play a significant part. An assessment of these measures must include consideration of their nonproliferation effectiveness as well as their bearing upon energy security, and their operational, economic, and political implications. The nature of these considerations can provide some measure of their likely acceptability to various nations. While any final assessment of such measures and alternatives would have to examine the circumstances particular to each nation, it is hoped that the more generic assessments conducted here will be useful in suggesting guidelines for developing an improved nonproliferation regime which also helps to meet nuclear-energy needs. One chapter outlines the existing nonproliferation regime, including the Treaty for the Non-Proliferation of Nuclear Weapons (NPT), International Atomic Energy Agency (IAEA) safeguards, bilateral and multilateral requirements for agreements of cooperation and transfers of technology, and existing provisons for sanctions for violation of nonproliferation commitments. The chapter then proceeds to an assessment of various alternatives for providing assurance of fuel supply in light of this current regime. Another chapter examines a set of technical and institutional measures and alternatives for various components of once-through and closed fuel cycles. The components of the once-through fuel cycle assessed are enrichment services and spent-fuel management; the components of closed fuel cycles assessed are reprocessing and plutonium management and fast-breeder reactor (FBR) deployment.

  12. Nuclear proliferation and civilian nuclear power. Report of the Nonproliferation Alternative Systems Assessment Program. Volume VII. International perspectives

    Energy Technology Data Exchange (ETDEWEB)

    1980-06-01

    The purpose of this volume is to assess the proliferation vulnerabilities of the present deployment of civilian nuclear-power systems within the current nonproliferation regime and, in light of their prospective deployment, to consider technical and institutional measures and alternatives which may contribute to an improved regime in which nuclear power could play a significant part. An assessment of these measures must include consideration of their nonproliferation effectiveness as well as their bearing upon energy security, and their operational, economic, and political implications. The nature of these considerations can provide some measure of their likely acceptability to various nations.

  13. The year 2000 examination conference of the non-proliferation treaty and the future of the nuclear non-proliferation regime; La conference d'examen 2000 du TNP et l'avenir du regime de non-proliferation nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Grand, C. [Institut d' Etudes Politiques de Paris, 75 (France); Ecole Speciale Militaire de Saint-Cyr-Coetquidan (France)

    2001-07-01

    The nuclear weapons non-proliferation treaty (NPT), signed on July 1, 1968 and enforced on March 5, 1970, has been progressively considered as the headstone of the international non-proliferation and disarmament regime. The sixth NPT examination conference took place at New York (USA) in the year 2000, 5 years after the previous conference but also after the first nuclear weapon tests of India and Pakistan. This article recalls up the main non-proliferation events that took place between the 1995 and 2000 conferences and presents the progresses and results of the New York conference. Finally, it wonders about the ambiguities in the conclusions of this last conference. (J.S.)

  14. The Non-Proliferation Treaty increases security; Pysyvae ydinsulkusopimus lisaeae kansainvaelistae vakautta

    Energy Technology Data Exchange (ETDEWEB)

    Kahiluoto, K.

    1995-12-31

    Extension of the Nuclear Non-Proliferation Treaty indefinitely was a historic decision. The Treaty is the most extensive international agreement on security policy to date; now its obligations have become a permanent part of international justice. Moreover, the NPT represents a political and moral obligation. Through the NPT, the international community has made a permanent commitment to restrict the proliferation of nuclear weapons. Increasing pressures will be applied to the few countries still outside the NPT, making it more likely that these countries will eventually change their views. The likelihood of regional bans on nuclear weapons in the Middle East and in Asia, too, will increase. The Treaty promotes the establishment of new nuclear-free zones. The nuclear-free zone in Latin America - the countries covered by the Tlatelolco Treaty - is already very close to its full implementation. Finland is firmly committed to the obligations of the Non-Proliferation Treaty. The NPT Conference of 1995 was among the first international meetings in which Finland participated, and took an active role, as a Member State of the European Union. (orig.).

  15. The Future of Nonproliferation in a Changed and Changing Environment: A Workshop Summary

    Energy Technology Data Exchange (ETDEWEB)

    Dreicer, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-30

    The Center for Global Security Research and Global Security Principal Directorate at Lawrence Livermore National Laboratory convened a workshop in July 2016 to consider “The Future of Nonproliferation in a Changed and Changing Security Environment.” We took a broad view of nonproliferation, encompassing not just the treaty regime but also arms control, threat reduction, counter-­proliferation, and countering nuclear terrorism. We gathered a group of approximately 60 experts from the technical, academic, political, defense and think tank communities and asked them what—and how much—can reasonably be accomplished in each of these areas in the 5 to 10 years ahead. Discussion was on a not-­for-­attribution basis. This document provides a summary of key insights and lessons learned, and is provided to help stimulate broader public discussion of these issues. It is a collection of ideas as informally discussed and debated among a group of experts. The ideas reported here are the personal views of individual experts and should not be attributed to Lawrence Livermore National Laboratory.

  16. Myeloid dendritic cells induce HIV-1 latency in non-proliferating CD4+ T cells.

    Science.gov (United States)

    Evans, Vanessa A; Kumar, Nitasha; Filali, Ali; Procopio, Francesco A; Yegorov, Oleg; Goulet, Jean-Philippe; Saleh, Suha; Haddad, Elias K; da Fonseca Pereira, Candida; Ellenberg, Paula C; Sekaly, Rafick-Pierre; Cameron, Paul U; Lewin, Sharon R

    2013-01-01

    Latently infected resting CD4(+) T cells are a major barrier to HIV cure. Understanding how latency is established, maintained and reversed is critical to identifying novel strategies to eliminate latently infected cells. We demonstrate here that co-culture of resting CD4(+) T cells and syngeneic myeloid dendritic cells (mDC) can dramatically increase the frequency of HIV DNA integration and latent HIV infection in non-proliferating memory, but not naïve, CD4(+) T cells. Latency was eliminated when cell-to-cell contact was prevented in the mDC-T cell co-cultures and reduced when clustering was minimised in the mDC-T cell co-cultures. Supernatants from infected mDC-T cell co-cultures did not facilitate the establishment of latency, consistent with cell-cell contact and not a soluble factor being critical for mediating latent infection of resting CD4(+) T cells. Gene expression in non-proliferating CD4(+) T cells, enriched for latent infection, showed significant changes in the expression of genes involved in cellular activation and interferon regulated pathways, including the down-regulation of genes controlling both NF-κB and cell cycle. We conclude that mDC play a key role in the establishment of HIV latency in resting memory CD4(+) T cells, which is predominantly mediated through signalling during DC-T cell contact.

  17. Myeloid dendritic cells induce HIV-1 latency in non-proliferating CD4+ T cells.

    Directory of Open Access Journals (Sweden)

    Vanessa A Evans

    Full Text Available Latently infected resting CD4(+ T cells are a major barrier to HIV cure. Understanding how latency is established, maintained and reversed is critical to identifying novel strategies to eliminate latently infected cells. We demonstrate here that co-culture of resting CD4(+ T cells and syngeneic myeloid dendritic cells (mDC can dramatically increase the frequency of HIV DNA integration and latent HIV infection in non-proliferating memory, but not naïve, CD4(+ T cells. Latency was eliminated when cell-to-cell contact was prevented in the mDC-T cell co-cultures and reduced when clustering was minimised in the mDC-T cell co-cultures. Supernatants from infected mDC-T cell co-cultures did not facilitate the establishment of latency, consistent with cell-cell contact and not a soluble factor being critical for mediating latent infection of resting CD4(+ T cells. Gene expression in non-proliferating CD4(+ T cells, enriched for latent infection, showed significant changes in the expression of genes involved in cellular activation and interferon regulated pathways, including the down-regulation of genes controlling both NF-κB and cell cycle. We conclude that mDC play a key role in the establishment of HIV latency in resting memory CD4(+ T cells, which is predominantly mediated through signalling during DC-T cell contact.

  18. MBE growth of self-assisted InAs nanowires on graphene

    Science.gov (United States)

    Kang, Jung-Hyun; Ronen, Yuval; Cohen, Yonatan; Convertino, Domenica; Rossi, Antonio; Coletti, Camilla; Heun, Stefan; Sorba, Lucia; Kacman, Perla; Shtrikman, Hadas

    2016-11-01

    Self-assisted growth of InAs nanowires on graphene by molecular beam epitaxy is reported. Nanowires with diameter of ∼50 nm and aspect ratio of up to 100 were achieved. The morphological and structural properties of the nanowires were carefully studied by changing the substrate from bilayer graphene through buffer layer to quasi-free-standing monolayer graphene. The positional relation of the InAs NWs with the graphene substrate was determined. A 30° orientation configuration of some of the InAs NWs is shown to be related to the surface corrugation of the graphene substrate. InAs NW-based devices for transport measurements were fabricated, and the conductance measurements showed a semi-ballistic behavior. In Josephson junction measurements in the non-linear regime, multiple Andreev reflections were observed, and an inelastic scattering length of about 900 nm was derived.

  19. MBE growth of self-assisted InAs nanowires on graphene

    CERN Document Server

    Kang, Jung-Hyun; Cohen, Yonatan; Convertino, Domenica; Rossi, Antonio; Coletti, Camilla; Heun, Stefan; Sorba, Lucia; Kacman, Perla; Shtrikman, Hadas

    2016-01-01

    Self-assisted growth of InAs nanowires on graphene by molecular beam epitaxy is reported. Nanowires with diameter of ~50 nm and aspect ratio of up to 100 were achieved. The morphological and structural properties of the nanowires were carefully studied by changing the substrate from bilayer graphene through buffer layer to quasi-free-standing monolayer graphene. The positional relation of the InAs NWs with the graphene substrate was determined. A 30{\\deg} orientation configuration of some of the InAs NWs is shown to be related to the surface corrugation of the graphene substrate. InAs NW-based devices for transport measurements were fabricated, and the conductance measurements showed a semi-ballistic behavior. In Josephson junction measurements in the non-linear regime, Multiple Andreev Reflections were observed, and an inelastic scattering length of about 900 nm was derived.

  20. Evolution of self-assembled InAs quantum dot molecules by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Tangmettajittakul, Ong-arj; Thainoi, Supachok; Panyakeow, Somsak; Ratanathammaphan, Somchai [Semiconductor Device Research Laboratory (Nanotech Center of Excellence), Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok (Thailand)

    2012-07-15

    Self-assembled InAs quantum dot molecules (QDMs) have been grown by thin-capping-and-regrowth MBE technique. The QDM-forming conditions have been changed by varying InAs growth rate in the range of 0.01-0.03 ML/s. We found that the InAs growth rate affects nano-propeller shape, dot density, and dot height. The densities of QDs, nano-propellers, and QDMs are increasing while increasing the InAs growth rate. In contrast, the dot height and the length of propeller blades are contrary to growth rate. Also, the uniformity of dots in QDMs can be changed by an increase of growth rate. These results are confirmed by photoluminescence (PL) measurement (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Defect reaction network in Si-doped InAs. Numerical predictions.

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Peter A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    This Report characterizes the defects in the def ect reaction network in silicon - doped, n - type InAs predicted with first principles density functional theory. The reaction network is deduced by following exothermic defect reactions starting with the initially mobile interstitial defects reacting with common displacement damage defects in Si - doped InAs , until culminating in immobile reaction p roducts. The defect reactions and reaction energies are tabulated, along with the properties of all the silicon - related defects in the reaction network. This Report serves to extend the results for the properties of intrinsic defects in bulk InAs as colla ted in SAND 2013 - 2477 : Simple intrinsic defects in InAs : Numerical predictions to include Si - containing simple defects likely to be present in a radiation - induced defect reaction sequence . This page intentionally left blank

  2. Enhancement of below gap transmission of InAs single crystal via suppression of native defects

    Science.gov (United States)

    Shen, Guiying; Zhao, Youwen; Dong, Zhiyuan; Liu, Jingming; Xie, Hui; Bai, Yongbiao; Chen, Xiaoyu

    2017-03-01

    As-grown and annealed undoped n type InAs single crystals have been studied by Hall effect measurement, infrared transmission (IR) spectroscopy, photoluminescence spectroscopy (PL) and glow discharge mass spectroscopy (GDMS). After annealing, below-gap infrared transmittance of the InAs single crystal increases significantly with the annihilation of a 0.383 eV PL peak related defect. Mechanism of the transmission enhancement and the attribution of the defect is discussed based on the experimental results.

  3. Evolution of Wurtzite Structured GaAs Shells Around InAs Nanowire Cores

    Directory of Open Access Journals (Sweden)

    Kim Y

    2009-01-01

    Full Text Available Abstract GaAs was radially deposited on InAs nanowires by metal–organic chemical vapor deposition and resultant nanowire heterostructures were characterized by detailed electron microscopy investigations. The GaAs shells have been grown in wurtzite structure, epitaxially on the wurtzite structured InAs nanowire cores. The fundamental reason of structural evolution in terms of material nucleation and interfacial structure is given.

  4. Defect-free thin InAs nanowires grown using molecular beam epitaxy.

    Science.gov (United States)

    Zhang, Zhi; Chen, Ping-Ping; Lu, Wei; Zou, Jin

    2016-01-21

    In this study, we designed a simple method to achieve the growth of defect-free thin InAs nanowires with a lateral dimension well below their Bohr radius on different substrate orientations. By depositing and annealing a thin layer of Au thin film on a (100) substrate surface, we have achieved the growth of defect-free uniform-sized thin InAs nanowires. This study provides a strategy to achieve the growth of pure defect-free thin nanowires.

  5. A RHEED/MBE-STM investigation of the static and dynamic InAs(001) surface

    Science.gov (United States)

    Bomphrey, J. J.; Ashwin, M. J.; Jones, T. S.

    2017-02-01

    We report here the temperature-dependent incorporation kinetics of dimeric arsenic in InAs(001) homoepitaxy, using reflection high-energy electron diffraction (RHEED). Surface reconstructions, in combination with the RHEED investigation have provided insight into the growth of InAs(001), developing an accurate method of controlling the V:III ratio, which has been utilised to probe the low temperature epitaxial growth of indium arsenide epitaxial layers.

  6. Awareness of the Vysočina Regional Food Labels With Context of Their Media Presence

    Directory of Open Access Journals (Sweden)

    Martina Chalupová

    2016-01-01

    Full Text Available The article presents results of research study that focused on the recognition of the Vysočina regional labels among the consumers in the region in connection with media analysis about the topic. Research among consumers was conducted in each district of Vysočina Region (Jihlava, Žďár nad Sázavou, Třebíč, Havlíčkův Brod and Pelhřimov by interviewing a sample of 819 respondents, selected by quota sampling methods. The research was aimed at analysing the ability of respondents to recognise and differentiate two existing regional labels VYSOČINA Regional Product®, Regional Food Vysočina Region and also nonexistent brand From Our Region Vysočina, created by authors. Data have been processed with correspondence analysis and showed that respondents connect different characteristics with the labels. Media analysis of the Vysočina regional labels revealed that media may help building awareness about the labels but they do not shape respondents’ views on them. Examining the link between the frequency of different types of information in media and their potential impact on the labels’ pereception by consumers have shown distorted image. Stronger consensus between research and media analysis have been examined only on importance of products’ origin, which can be viewed as a logical inference from the name of the labels.

  7. 77 FR 51545 - Exercise of Authority Under the Immigration and Nationality Act

    Science.gov (United States)

    2012-08-24

    ... SECURITY Office of the Secretary Exercise of Authority Under the Immigration and Nationality Act AGENCY... Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as well as the foreign policy.... Implementation of this determination will be made by U.S. Citizenship and Immigration Services (USCIS),...

  8. 78 FR 24225 - Exercise of Authority Under the Immigration and Nationality Act

    Science.gov (United States)

    2013-04-24

    ... SECURITY Office of the Secretary Exercise of Authority Under the Immigration and Nationality Act AGENCY... Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as well as the foreign policy.... Implementation of this determination will be made by U.S. Citizenship and Immigration Services (USCIS),...

  9. 75 FR 82242 - Visas: Waiver for Ineligible Nonimmigrants Under the Immigration and Nationality Act

    Science.gov (United States)

    2010-12-30

    ... Part 40 Visas: Waiver for Ineligible Nonimmigrants Under the Immigration and Nationality Act AGENCY: State Department. ACTION: Final rule. SUMMARY: This rule incorporates a revision to the Immigration and... relative to the grounds of inadmissibility under the Immigration and Nationality Act (INA) for...

  10. 76 FR 70463 - Exercise of Authority Under the Immigration and Nationality Act

    Science.gov (United States)

    2011-11-14

    ... SECURITY Office of the Secretary Exercise of Authority Under the Immigration and Nationality Act AGENCY... Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as well as the foreign policy... by U.S. Citizenship and Immigration Services (USCIS), in consultation with U.S. Immigration...

  11. 78 FR 66037 - Exercise of Authority Under the Immigration and Nationality Act

    Science.gov (United States)

    2013-11-04

    ... SECURITY Office of the Secretary Exercise of Authority Under the Immigration and Nationality Act AGENCY... Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as well as the foreign policy... made by U.S. Citizenship and Immigration Services (USCIS), in consultation with U.S. Immigration...

  12. 78 FR 66036 - Exercise of Authority Under the Immigration and Nationality Act

    Science.gov (United States)

    2013-11-04

    ... SECURITY Office of the Secretary Exercise of Authority Under the Immigration and Nationality Act AGENCY... Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as well as the foreign policy... made by U.S. Citizenship and Immigration Services (USCIS), in consultation with U.S. Immigration...

  13. Oxidation and etching behaviors of the InAs surface in various acidic and basic chemical solutions

    Science.gov (United States)

    Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo

    2017-04-01

    Indium arsenide (InAs) is the candidate of choice as a new channel material for application in future technologies beyond the Si-based electronic devices because it has a much higher electron mobility than silicon. In this study, the oxidation and etching behaviors of InAs (100) in various acidic and basic solutions, such as HF, HCl, H2SO4, NaOH, KOH, and NH4OH, were investigated. In addition, the effect of pH on the oxidation and etching reactions taking place on the InAs surface was studied using solutions with a pH ranging from 1 to 13. It was observed that the oxidation of the InAs surface was hindered in acidic solutions, which was attributed to the dissolution of the oxidized surface layer. In particular, the treatment of the InAs surface using a strongly acidic solution with a pH of less than 3 produced an oxide-free surface due to the predominant etching of the InAs surface. The addition of H2O2 to the acidic solutions greatly increased the etching rate of the InAs surface, which suggests that the oxidation process is the rate-limiting step in the sequence of reactions that occur during the etching of the InAs surface in acidic solutions. The etching of InAs was suppressed in neutral solutions, which resulted in the formation of a relatively thicker oxide layer on the surface, and mild etching of the InAs surface took place in basic solutions. However, in basic solutions, the addition of H2O2 did not significantly contribute to the increase of the oxidation state of the InAs surface; thus, its effect on the etching rate of InAs was smaller than in acidic solutions.

  14. Report of a Workshop in Nuclear Forces and Nonproliferation held at the Woodrow Wilson International Center for Scholars, Washington, DC

    Energy Technology Data Exchange (ETDEWEB)

    Pilat, Joseph F [Los Alamos National Laboratory

    2009-01-01

    The workshop addressed evolving nuclear forces and their impacts on nonproliferation in the context of the new strategic environment, the Obama Administration's Nuclear Posture Review (NPR) Review and the 2010 Conference (RevCon) of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). The issues discussed are at the heart of the debate on nuclear policy issues such asfuture nuclear weapons requirements and nonproliferation, but also the stockpile stewardship program and infrastructure modernization. The workshop discussions reflected the importance of the NPRfor defining the role of US nuclear forces in dealing with 21s1 century threats and providing guidance that will shape NNSA and DoD programs. They also highlighted its importancefor NPT diplomacy. The discussion noted the report of the bipartisan Congressional Commission on the Strategic Posture of the United States, and the expectation that the NPR would likely reflect its consensus to a large degree (although the Administration was not bound by the report). There was widespread support for developing thefoundationsfor a sustainable nuclear-weapon program that addresses nuclear weapons, infrastructure and expertise in the broader nonproliferation, disarmament and international security contexts. The discussion also revealed a convergence of views, but no consensus, on a number of important issues, including the diminished role but continued importance of nuclear weapons; the need to take action to ensure the sustainability of the stockpile, and the recapitalization of the infrastructure and expertise; and the need to take action to promote nonproliferation, arms control and disarmament objectives.

  15. Nonproliferation impacts assessment for the management of the Savannah River Site aluminum-based spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    On May 13, 1996, the US established a new, 10-year policy to accept and manage foreign research reactor spent nuclear fuel containing uranium enriched in the US. The goal of this policy is to reduce civilian commerce in weapons-usable highly enriched uranium (HEU), thereby reducing the risk of nuclear weapons proliferation. Two key disposition options under consideration for managing this fuel include conventional reprocessing and new treatment and packaging technologies. The Record of Decision specified that, while evaluating the reprocessing option, ``DOE will commission or conduct an independent study of the nonproliferation and other (e.g., cost and timing) implications of chemical separation of spent nuclear fuel from foreign research reactors.`` DOE`s Office of Arms Control and Nonproliferation conducted this study consistent with the aforementioned Record of Decision. This report addresses the nonproliferation implications of the technologies under consideration for managing aluminum-based spent nuclear fuel at the Savannah River Site. Because the same technology options are being considered for the foreign research reactor and the other aluminum-based spent nuclear fuels discussed in Section ES.1, this report addresses the nonproliferation implications of managing all the Savannah River Site aluminum-based spent nuclear fuel, not just the foreign research reactor spent nuclear fuel. The combination of the environmental impact information contained in the draft EIS, public comment in response to the draft EIS, and the nonproliferation information contained in this report will enable the Department to make a sound decision regarding how to manage all aluminum-based spent nuclear fuel at the Savannah River Site.

  16. Metalorganic vapour epitaxial growth and infrared characterisation of InAsSb and InAs on InAs substrates

    CSIR Research Space (South Africa)

    Baisitse, TR

    2006-07-01

    Full Text Available Motivation for the research: Interest exists in III-V semiconducting materials (InAs, GaSb, InSb and related alloys) for the detection of infrared radiation; Such materials could be used as alternatives for future infrared detectors and various...

  17. Nuclear disarmament. Options for the coming non-proliferation treaty surveillance cycle; Nukleare Abruestung. Optionen fuer den kommenden Ueberpruefungszyklus des NVV

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Harald

    2011-07-01

    The report is aimed on the nuclear disarmament discussion with respect to the disagreement of nuclear weapon states and those without nuclear weapons, esp. the non-aligned movement (NAM) concerning the non-proliferation treaty. The report covers the following issues: The role of the non-proliferation treaty, nuclear disarmament in the last surveillance conference 2010, the different disarmament philosophies, the possibilities of bridging the disagreement, further disarmament options for the future non-proliferation treaty surveillance cycle, German options for the future surveillance cycle.

  18. The European Safeguards Research and Development Association Addresses Safeguards and Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Janssens-Maenhout, Greet; Kusumi, R.; Daures, Pascal A.; Janssens, Willem; Dickman, Deborah A.

    2010-06-16

    The renaissance of efforts to expand the use of nuclear energy requires the parallel development of a renewed and more sophisticated work force. Growth in the nuclear sector with high standard of safety, safeguards and security requires skilled staff for design, operations, inspections etc. High-quality nuclear technology educational programs are diminished from past years, and the ability of universities to attract students and to meet future staffing requirements of the nuclear industry is becoming seriously compromised. Thus, education and training in nuclear engineering and sciences is one of the cornerstones for the nuclear sector. Teaching in the nuclear field still seems strongly influenced by national history but it is time to strengthen resources and collaborate. Moreover with the current nuclear security threats it becomes critical that nuclear technology experts master the basic principles not only of safety, but also of nuclear safeguards, nonproliferation and nuclear security. In Europe the European Nuclear Education Network (ENEN) Association has established the certificate 'European Master of Science in Nuclear Engineering (EMSNE)' as the classic nuclear engineering program covering reactor operation and nuclear safety. However, it does not include courses on nonproliferation, safeguards, or dual-use technologies. The lack of education in nuclear safeguards was tackled by the European Safeguards Research and Development Association (ESARDA), through development and implementation of safeguards course modules. Since 2005 the ESARDA Working Group, called the Training and Knowledge Management Working Group, (TKMWG) has worked with the Joint Research Centre (JRC) in Ispra, Italy to organize a Nuclear Safeguards and Nonproliferation course. This five-day course is held each spring at the JRC, and continues to show increasing interest as evidenced by the positive responses of international lecturers and students. The standard set of lectures

  19. Airborne Multisensor Pod System, Arms control and nonproliferation technologies: Second quarter 1995

    Energy Technology Data Exchange (ETDEWEB)

    Alonzo, G M; Sanford, N M [eds.

    1995-01-01

    This issue focuses on the Airborne Multisensor Pod System (AMPS) which is a collaboration of many of the DOE national laboratories to provide a scientific environment to research multiple sensors and the new information that can be derived from them. The bulk of the research has been directed at nonproliferation applications, but it has also proven useful in environmental monitoring and assessment, and land/water management. The contents of this issue are: using AMPS technology to detect proliferation and monitor resources; combining multisensor data to monitor facilities and natural resources; planning a AMPS mission; SAR pod produces images day or night, rain or shine; MSI pod combines data from multiple sensors; ESI pod will analyze emissions and effluents; and accessing AMPS information on the Internet.

  20. National Nuclear Security Administration Nonproliferation Graduate Fellowship Program Annual Report in Brief: October 2007 - May 2008

    Energy Technology Data Exchange (ETDEWEB)

    Berkman, Clarissa O.; Fankhauser, Jana G.; Sandusky, Jessica A.

    2009-05-01

    This abbreviated Annual Report covers program activities of the National Nuclear Security Administration (NNSA) Nonproliferation Graduate Fellowship Program (NGFP) from October 2007 through May 2008--the timeframe between the last Annual Report (which covered activities through September 2007) and the next report (which will begin with June 2008 activities). In that timeframe, the NGFP continued building a solid foundation as the program began reaping the benefits of recently implemented changes. This report is organized by Fellowship class and the pertinent program activities for each, including: October 2007 Recruiting events and final applications (Class of 2008) Winter 2007 Selection and hiring (Class of 2008) Spring 2008 Career development roundtables (Class of 2007) Orientation planning (Class of 2008) Recruitment planning and university outreach (Class of 2009) May 2008 Closing ceremony (Class of 2007)

  1. Stabilization and immobilization of military plutonium: A non-proliferation perspective

    Energy Technology Data Exchange (ETDEWEB)

    Leventhal, P. [Nuclear Control Institute, Washington, DC (United States)

    1996-05-01

    The Nuclear Control Institute welcomes this DOE-sponsored technical workshop on stabilization and immobilization of weapons plutonium (W Pu) because of the significant contribution it can make toward the ultimate non-proliferation objective of eliminating weapons-usable nuclear material, plutonium and highly enriched uranium (HEU), from world commerce. The risk of theft or diversion of these materials warrants concern, as only a few kilograms in the hands of terrorists or threshold states would give them the capability to build nuclear weapons. Military plutonium disposition questions cannot be addressed in isolation from civilian plutonium issues. The National Academy of Sciences has urged that {open_quotes}further steps should be taken to reduce the proliferation risks posed by all of the world`s plutonium stocks, military and civilian, separated and unseparated...{close_quotes}. This report discusses vitrification and a mixed oxide fuels option, and the effects of disposition choices on civilian plutonium fuel cycles.

  2. Non-proliferation, safeguards, and security for the fissile materials disposition program immobilization alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Duggan, R.A.; Jaeger, C.D.; Tolk, K.M. [Sandia National Labs., Albuquerque, NM (United States); Moore, L.R. [Lawrence Livermore National Lab., CA (United States)

    1996-05-01

    The Department of Energy is analyzing long-term storage and disposition alternatives for surplus weapons-usable fissile materials. A number of different disposition alternatives are being considered. These include facilities for storage, conversion and stabilization of fissile materials, immobilization in glass or ceramic material, fabrication of fissile material into mixed oxide (MOX) fuel for reactors, use of reactor based technologies to convert material into spent fuel, and disposal of fissile material using geologic alternatives. This paper will focus on how the objectives of reducing security and proliferation risks are being considered, and the possible facility impacts. Some of the areas discussed in this paper include: (1) domestic and international safeguards requirements, (2) non-proliferation criteria and measures, (3) the threats, and (4) potential proliferation, safeguards, and security issues and impacts on the facilities. Issues applicable to all of the possible disposition alternatives will be discussed in this paper. However, particular attention is given to the plutonium immobilization alternatives.

  3. Recent progress in high gain InAs avalanche photodiodes (Presentation Recording)

    Science.gov (United States)

    Bank, Seth; Maddox, Scott J.; Sun, Wenlu; Nair, Hari P.; Campbell, Joe C.

    2015-08-01

    InAs possesses nearly ideal material properties for the fabrication of near- and mid-infrared avalanche photodiodes (APDs), which result in strong electron-initiated impact ionization and negligible hole-initiated impact ionization [1]. Consequently, InAs multiplication regions exhibit several appealing characteristics, including extremely low excess noise factors and bandwidth independent of gain [2], [3]. These properties make InAs APDs attractive for a number of near- and mid-infrared sensing applications including remote gas sensing, light detection and ranging (LIDAR), and both active and passive imaging. Here, we discuss our recent advances in the growth and fabrication of high gain, low noise InAs APDs. Devices yielded room temperature multiplication gains >300, with much reduced (~10x) lower dark current densities. We will also discuss a likely key contributor to our current performance limitations: silicon diffusion into the intrinsic (multiplication) region from the underlying n-type layer during growth. Future work will focus on increasing the intrinsic region thickness, targeting gains >1000. This work was supported by the Army Research Office (W911NF-10-1-0391). [1] A. R. J. Marshall, C. H. Tan, M. J. Steer, and J. P. R. David, "Electron dominated impact ionization and avalanche gain characteristics in InAs photodiodes," Applied Physics Letters, vol. 93, p. 111107, 2008. [2] A. R. J. Marshall, A. Krysa, S. Zhang, A. S. Idris, S. Xie, J. P. R. David, and C. H. Tan, "High gain InAs avalanche photodiodes," in 6th EMRS DTC Technical Conference, Edinburgh, Scotland, UK, 2009. [3] S. J. Maddox, W. Sun, Z. Lu, H. P. Nair, J. C. Campbell, and S. R. Bank, "Enhanced low-noise gain from InAs avalanche photodiodes with reduced dark current and background doping," Applied Physics Letters, vol. 101, no. 15, pp. 151124-151124-3, Oct. 2012.

  4. Restriction of Civilian Nuclear Fuel Cycle and Effectiveness of Nuclear Nonproliferation

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, JaeSoo; Lee, HanMyung; Ko, HanSuk; Yang, MaengHo; Oh, KunBae [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2006-07-01

    Many efforts have been made to prevent the spread of nuclear weapons since the nuclear era. Recent revelation such as Dr. A.Q. Khan Network showed that some states had acquired sensitive nuclear technologies including uranium enrichment which could be used for making nuclear weapons. In addition, with the advancement of industrial technology, it has become easier to have access to those technologies. In this context, proliferation risks are being increased more and more. As a result, various proposals to respond to proliferation risks by sensitive technologies have been made: Multilateral Nuclear Approaches (MNAs) by IAEA Director General El Baradei, non-transfer of sensitive nuclear technologies by the U.S. President George W. Bush, international center for nuclear fuel cycle service by Russian President Vladimir V. Putin, Global Nuclear Energy Partnership (GNEP) by Bush's administration and a concept for a multilateral mechanism for reliable access to nuclear fuel by 6 member states of the IAEA. Theses proposals all share the idea that the best way to reduce risk is to prevent certain states from having control over an indigenous civilian fuel cycle while still finding ways to confer the benefits of nuclear energy, and seem to imply that the current nonproliferation regime is fundamentally flawed and needs to be altered. However, these proposals are a center of controversy because they can restrict the inalienable right for the peaceful purposes of nuclear energy inscribed in Article IV of the NPT. Therefore, this paper analyzes the key challenges of these proposals and effectiveness of the goal of nuclear nonproliferation in practical term by restricting civilian nuclear fuel cycle.

  5. Growth of Catalyst-Free Epitaxial InAs Nanowires on Si Wafers Using Metallic Masks.

    Science.gov (United States)

    Soo, M Teng; Zheng, Kun; Gao, Qiang; Tan, H Hoe; Jagadish, Chennupati; Zou, Jin

    2016-07-13

    Development of heteroepitaxy growth of catalyst-free vertical III-V nanowires on Si wafers is highly desirable for future nanoscale Si-based electronic and optoelectronic devices. In this study, a proof-of-concept approach is developed for catalyst-free heteroepitaxy growth of InAs nanowires on Si wafers. Before the growth of InAs nanowires, a Si-compatible metallic film with a thickness of several tens of nanometers was predeposited on a Si wafer and then annealed to form nanosize openings so as to obtain a metallic mask. These nano-openings exposed the surface of the Si wafer, which allowed subsequent nucleation and growth of epitaxial InAs nanowires directly on the surface of the Si wafer. The small size of the nano-openings limits the lateral growth of the nanostructures but promotes their axial growth. Through this approach, catalyst-free InAs nanowires were grown on both Si (111) and (001) wafers successfully at different growth temperatures. In particular, ultralong defect-free InAs nanowires with the wurtzite structure were grown the Si (111) wafers at 550 °C using the Ni mask. This study offers a simple, cost-effective, and scalable method to grow catalyst-free III-V nanowires on Si wafers. The simplicity of the approach opens a new avenue for the growth and integration of catalyst-free high-quality heteroepitaxial III-V nanowires on Si wafers.

  6. MOVPE growth of InAs quantum dots for mid-IR applications

    Institute of Scientific and Technical Information of China (English)

    TANG Xiao-hong; YIN Zong-you; DU An-yan; ZHAO Jing-hua; DENY S

    2006-01-01

    InAs quantum dots (QDs) grown on InxGa1-xAs/InP matrix by low pressure metal organic vapor phase epitaxy (LP-MOVPE) in nitrogen ambient were studied. Formation of the InAs QDs with different growth conditions was investigated. To improve the dot size uniformity,a two-step growth method was used and investigated. It is found that morphology of the InAs QDs formed on such InxGa1-xAs/InP matrix is very sensitive to the growth conditions. InAs QDs with high density of 1.3×1010 cm-2 are grown by using S-K growth method with fast growth rate. Using the two-step growth method,the InAs QDs size uniformity improves by 63% and 110% compared that of the dots grown by ordinary S-K method and ALE method,respectively. Narrow photoluminescence (PL) emission spectrum of the QDs grown by using the two-step growth method is received. FWHM of the PL curve is measured at 26 meV and the peak emission wavelength is larger than 2.3 μm at 77 K.

  7. InAs quantum dots as charge storing elements for applications in flash memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Sk Masiul; Biswas, Pranab [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Banerji, P., E-mail: pallab@matsc.iitkgp.ernet.in [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India)

    2015-08-15

    Graphical abstract: - Highlights: • Catalyst-free growth of InAs quantum dots was carried out on high-k ZrO{sub 2}. • Memory device with InAs quantum dots as charge storage nodes are fabricated. • Superior memory window, low leakage and reasonably good retention were observed. • Carrier transport phenomena are explained in both program and erase operations. - Abstract: InAs quantum dots (QDs) were grown by metal organic chemical vapor deposition technique to use them as charge storage nodes. Uniform QDs were formed with average diameter 5 nm and height 5–10 nm with a density of 2 × 10{sup 11} cm{sup −2}. The QDs were grown on high-k dielectric layer (ZrO{sub 2}), which was deposited onto ultra-thin GaP passivated p-GaAs (1 0 0) substrate. A charge storage device with the structure Metal/ZrO{sub 2}/InAs QDs/ZrO{sub 2}/(GaP)GaAs/Metal was fabricated. The devices containing InAs QDs exhibit superior memory window, low leakage current density along with reasonably good charge retention. A suitable electronic band diagram corresponding to programming and erasing operations was proposed to explain the operation.

  8. Synthesis and Diameter-dependent Thermal Conductivity of InAs Nanowires

    Institute of Scientific and Technical Information of China (English)

    Pinyun Ren; Minggang Xia; Anlian Pan; Xiaoli Zhu; Jinyun Han; Jinyou Xu; Liang Ma; Honglai Li; Xiujuan Zhuang; Hong Zhou; Qinglin Zhang

    2014-01-01

    In this work, we synthesized high-quality InAs nanowires by a convenient chemical vapor deposition method, and developed a simple laser heating method to measure the thermal conductivity of a single InAs nanowire in air. During the measurement, a focused laser was used to heat one end of a freely suspended nanowire, with its other end embedded into a carbon conductive adhesive. In order to obtain the thermal conductivity of InAs nanowires, the heat loss in the heat transfer process was estimated, which includes the heat loss through air conduction, the heat convection, and the radiation loss. The absorption ratio of the laser power in the InAs nanowire was calculated. The result shows that the thermal conductivity of InAs nanowires monotonically increases from 6.4 W m-1 K-1 to 10.5 W m-1 K-1 with diameters increasing from 100 nm to 190 nm, which is ascribed to the enhanced phonon-boundary scattering.

  9. Ag-catalyzed InAs nanowires grown on transferable graphite flakes

    Science.gov (United States)

    Meyer-Holdt, Jakob; Kanne, Thomas; Sestoft, Joachim E.; Gejl, Aske; Zeng, Lunjie; Johnson, Erik; Olsson, Eva; Nygård, Jesper; Krogstrup, Peter

    2016-09-01

    Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report on high aspect ratio and stacking fault free Ag-seeded InAs nanowires grown on exfoliated graphite flakes by molecular beam epitaxy. Ag catalyzes the InAs nanowire growth selectively on the graphite flakes and not on the underlying InAs substrates. This allows for easy transfer of the flexible graphite flakes with as-grown nanowire ensembles to arbitrary substrates by a micro-needle manipulator. Besides the possibilities for fabricating novel nanostructure device designs, we show how this method is used to study the parasitic growth and bicrystal match between the graphite flake and the nanowires by transmission electron microscopy.

  10. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  11. Modulation spectroscopy of InAs semiconductor nanostructures grown on (631) high index substrates

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Velis, I.; Rojas-Ramirez, J.S.; Contreras-Guerrero, R.; Ramirez-Lopez, M.; Hernandez-Rosas, J. [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Mexico D.F. (Mexico); Garcia-Linan, G.; Gorbatchev, A.Yu. [Optical Communications Research Institute (IICO), Universidad Autonoma de San Luis Potosi, San Luis Potosi(Mexico); Zamora-Peredo, L. [Universidad Politecnica de San Luis Potosi, San Luis Potosi (Mexico); Lopez-Lopez, M. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico (Mexico); Mendez-Garcia, Victor H.

    2009-05-15

    The molecular beam epitaxial (MBE) growth of InAs nanostructures on GaAs(631)-oriented substrates is studied by photoluminescence (PL) and photoreflectance spectroscopy (PR). First, a corrugated surface conformed by regularly spaced grooves aligned along the [ anti 593] azimuth was formed by the GaAs homoepitaxial growth on the (631) substrate. On this template, we proceeded with the deposition of InAs at several thicknesses in the range of 1 to 4.5 monolayers (MLs). An atomic force microscopy (AFM) analysis of samples without GaAs capping, revealed that assemblage of QDs occurs only after the deposition of the equivalent to {proportional_to}1.9 ML of InAs. On these samples, we observed changes on the PR line-shape in the near-bandgap GaAs region linked to the quantity of InAs deposited. The intensity of the built in electric fields was correlated with the strain state at the heterointerface, as a consequence of the self induced piezoelectric effect, typical from high index surfaces. On the other hand, when the samples were capped with a 100 Aa thick GaAs layer, strong emission of the nanostructures occurs even for deposited quantities of InAs as low as 1 ML. Since for this InAs thickness the self-assemblage of QDs is not observed, the optical transitions observed were associated with the optical emission of self assembled semiconductor quantum wires, promoted by surface diffusion anisotropy, characteristic of the (631) plane. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. High sensitivity InAs photodiodes for mid-infrared detection

    Science.gov (United States)

    Ng, Jo Shien; Zhou, Xinxin; Auckloo, Akeel; White, Benjamin; Zhang, Shiyong; Krysa, Andrey; David, John P. R.; Tan, Chee Hing

    2016-10-01

    Sensitive detection of mid-infrared light (2 to 5 μm wavelengths) is crucial to a wide range of applications. Many of the applications require high-sensitivity photodiodes, or even avalanche photodiodes (APDs), with the latter generally accepted as more desirable to provide higher sensitivity when the optical signal is very weak. Using the semiconductor InAs, whose bandgap is 0.35 eV at room temperature (corresponding to a cut-off wavelength of 3.5 μm), Sheffield has developed high-sensitivity APDs for mid-infrared detection for one such application, satellite-based greenhouse gases monitoring at 2.0 μm wavelength. With responsivity of 1.36 A/W at unity gain at 2.0 μm wavelength (84 % quantum efficiency), increasing to 13.6 A/W (avalanche gain of 10) at -10V, our InAs APDs meet most of the key requirements from the greenhouse gas monitoring application, when cooled to 180 K. In the past few years, efforts were also made to develop planar InAs APDs, which are expected to offer greater robustness and manufacturability than mesa APDs previously employed. Planar InAs photodiodes are reported with reasonable responsivity (0.45 A/W for 1550 nm wavelength) and planar InAs APDs exhibited avalanche gain as high as 330 at 200 K. These developments indicate that InAs photodiodes and APDs are maturing, gradually realising their potential indicated by early demonstrations which were first reported nearly a decade ago.

  13. Nonproliferation and arms control assessment of weapons-usable fissile material storage and excess plutonium disposition alternatives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    This report has been prepared by the Department of Energy`s Office of Arms Control and Nonproliferation (DOE-NN) with support from the Office of Fissile Materials Disposition (DOE-MD). Its purpose is to analyze the nonproliferation and arms reduction implications of the alternatives for storage of plutonium and HEU, and disposition of excess plutonium, to aid policymakers and the public in making final decisions. While this assessment describes the benefits and risks associated with each option, it does not attempt to rank order the options or choose which ones are best. It does, however, identify steps which could maximize the benefits and mitigate any vulnerabilities of the various alternatives under consideration.

  14. Ordered InAs Quantum Dots with Controllable Periods Grown on Stripe-Patterned GaAs Substrates

    Institute of Scientific and Technical Information of China (English)

    REN Yun-Yun; XU Bo; WANG Zhan-Guo; LIU Ming; LONG Shi-Bing

    2007-01-01

    GaAs (001) substrates are patterned by electron beam lithography and wet chemical etching to control the nucleation of lnAs quantum dots (QDs). InAs dots are grown on the stripe-patterned substrates by solid source molecular beam epitaxy. A thick buffer layer is deposited on the strip pattern before the deposition of InAs. To enhance the surface diffusion length of the In atoms, InAs is deposited with low growth rate and low As pressure.The AFM images show that distinct one-dimensionally ordered InAs QDs with homogeneous size distribution are created, and the QDs preferentially nucleate along the trench. With the increasing amount of deposited InAs and the spacing of the trenches, a number of QDs are formed beside the trenches. The distribution of additional QDs is long-range ordered, always along the trenchs rather than across the spacing regions.

  15. The new role of non-proliferation surveillance; Safeguards - die neue Rolle der Nichtverbreitungsueberwachung

    Energy Technology Data Exchange (ETDEWEB)

    Weh, R. [GNS Gesellschaft fuer Nuklear-Service mbH, Essen (Germany)

    2001-10-01

    Non-proliferation and nuclear safeguards are intimately connected with the peaceful development and use of nuclear power. The contractual obligation to forgo any misuse aimed at the construction of atom boms has been, and is, an important basis of all activities in the nuclear field. For the Federal Republic of Germany and the other participating states, subdivided into nuclear weapon states and non-nuclear-weapon states, the 1954 Brussels Treaty, which contains a fundamental clause waiving the production of nuclear weapons, the establishment of the European Atomic Energy Community, EURATOM, within the framework of the 1957 Treaties of Rome, and the Treaty on the Non-proliferation of Nuclear Weapons (Non-proliferation Treaty) within the framework of IAEA are the underlying basic legal instruments. These treaties, and the extended agreements based on them, operated on the basis of the 'old' system of surveillance of fissile material (nuclear safeguards). Both the inspection effort to be coped with by IAEA, which has kept rising steadily since the eighties and for which no additional budget funds were made available, and the violation by Iraq of the treaty as corroborated by a UN inspection team discovering a program for the production of weapons of mass destruction, boosted efforts in the early nineties to revise the existing system of treaties and controls. The International Atomic Energy Agency, among other measures, decided to improve nuclear safeguards by introducing immediate measures and optimization programs and upgrading inspection possibilities by a new model agreement. The model protocol, INFCIRC/153, adopted by the Board of Governors in September 1997 among other things serves to supplement the existing system of verification of the correctness of information received by another system verifying the completeness of such information. It incorporates an extended duty to supply information and extended rights of access. This includes activities not

  16. Time-resolved measurements of Cooper-pair radiative recombination in InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Mou, S. S.; Nakajima, H.; Kumano, H.; Suemune, I., E-mail: isuemune@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020 (Japan); Irie, H. [NTT Basic Research Laboratories, NTT Corporation, Atsugi 243-0198 (Japan); Asano, Y. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Akahane, K.; Sasaki, M. [National Institute of Information and Communication Technology, Koganei 184-8795 (Japan); Murayama, A. [Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan)

    2015-08-21

    We studied InAs quantum dots (QDs) where electron Cooper pairs penetrate from an adjacent niobium (Nb) superconductor with the proximity effect. With time-resolved luminescence measurements at the wavelength around 1550 nm, we observed luminescence enhancement and reduction of luminescence decay time constants at temperature below the superconducting critical temperature (T{sub C}) of Nb. On the basis of these measurements, we propose a method to determine the contribution of Cooper-pair recombination in InAs QDs. We show that the luminescence enhancement measured below T{sub C} is well explained with our theory including Cooper-pair recombination.

  17. Electrically Driven InAs Quantum-Dot Single-Photon Sources

    Institute of Scientific and Technical Information of China (English)

    XIONG Yong-Hua; NIU Zhi-Chuan; DOU Xiu-Ming; SUN Bao-Quan; HUANG She-Song; NI Hai-Qiao; DU Yun; XIA Jian-Bai

    2009-01-01

    Electrically driven single photon source based on single InAs quantum dot (QDs) is demonstrated. The device contains InAs QDs within a planar cavity formed between a bottom AIGaAs/GaAs distributed Bragg reflector (DBR) and a surface GaAs-air interface. The device is characterized by Ⅰ-Ⅴ curve and electroluminescence, and a single sharp exciton emission line at 966 nm is observed. Hanbury Brown and Twiss (HBT) correlation measurements demonstrate single photon emission with suppression of multiphoton emission to below 45% at 80 K

  18. Hall and thermoelectric evaluation of p-type InAs

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M.C., E-mail: magnus.wagener@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Wagener, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2009-12-15

    This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

  19. Assessment of Impact of Monoenergetic Photon Sources on Prioritized Nonproliferation Applications: Simulation Study Report

    Energy Technology Data Exchange (ETDEWEB)

    Geddes, Cameron [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ludewigt, Bernhard [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Valentine, John [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Quiter, Brian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Descalle, Marie-Anne [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Warren, Glen [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kinlaw, Matt [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Scott [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chichester, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, Cameron [Univ. of Michigan, Ann Arbor, MI (United States); Pozzi, Sara [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-12-30

    Near-monoenergetic photon sources (MPSs) have the potential to improve sensitivity at greatly reduced dose in existing applications and enable new capabilities in other applications. MPS advantages include the ability to select energy, energy spread, flux, and pulse structures to deliver only the photons needed for the application, while suppressing extraneous dose and background. Some MPSs also offer narrow divergence photon beams which can target dose and/or mitigate scattering contributions to image contrast degradation. Current broad-band, bremsstrahlung photon sources (e.g., linacs and betatrons) deliver unnecessary dose that in some cases also interferes with the signature to be detected and/or restricts operations, and must be collimated (reducing flux) to generate narrow divergence beams. While MPSs can in principle resolve these issues, they are technically challenging to produce. Candidate MPS technologies for nonproliferation applications are now being developed, each of which have different properties (e.g. broad divergence vs. narrow). Within each technology, source parameters trade off against one another (e.g. flux vs. energy spread), representing a large operation space. To guide development, requirements for each application of interest must be defined and simulations conducted to define MPS parameters that deliver benefit relative to current systems. The present project conducted a broad assessment of potential nonproliferation applications where MPSs may provide new capabilities or significant performance enhancement (reported separately), which led to prioritization of several applications for detailed analysis. The applications prioritized were: cargo screening and interdiction of Special Nuclear Materials (SNM), detection of hidden SNM, treaty/dismantlement verification, and spent fuel dry storage cask content verification. High resolution imaging for stockpile stewardship was considered as a sub-area of the treaty topic, as it is also of

  20. Germany and the nuclear non-proliferation; Current situation and prospects; Deutschland und die nukleare Nichtverbreitung; Zwischenbilanz und Ausblick

    Energy Technology Data Exchange (ETDEWEB)

    Preisinger, J.

    1993-07-01

    A summary is given of the consequences, both positive and negative, of international non-proliferation policy. The numerous, complex branches and connections of national measures and inter-stake agreements for the peaceful, controlled uses of nuclear technology and related military technologies are expertly described, and assessed on their effectiveness. Weak aspects of the nuclear non-proliferation regime are pointed out and past reforms are illustrated and assessed in the light of recent developments. The interests of the German Federal Republic from the centre of this analysis. The author shows that, after a certain hesitary, German diplomacy has now become active in the establishment of an international non-proliferation regime. He concludes that Germany should take a strong initiative role in maintaining a peaceful international nuclear order. (orig.) [Deutsch] Es wird ein Resuemee der bisherigen Erfolge und Misserfolge internationaler Nichtverbreitungspolitik gezogen. Die komplexen, vielfach veraestelten und verschachtelten nationalen Massnahmen und zwischenstaatlichen Vereinbarungen zur Ueberwachung und friedlichen Zweckbindung von Nukleartechnologie und militaerisch relevanten Anschlusstechnologien werden sachkundig erlaeutert und auf ihre Wirksamkeit ueberprueft. Schwachstellen des nuklearen Nichtverbreitungsregimes werden offengelegt, Reformschritte der vergangenen Jahre werden dargestellt und im Lichte der juengsten Entwicklungen bewertet. Dabei steht die Interessenlage der Bundesrepublik Deutschland im Zentrum der Analyse. Der Autor zeigt, dass die deutsche Diplomatie sich nach einer gewissen Zurueckhaltung schliesslich aktiv in die Gestaltung des internationalen Nichtverbreitungsregimes eingeschaltet hat. Er plaediert fuer eine kraftvolle Initiativrolle Deutschlands zur Erhaltung einer friedlichen internationalen Nuklearordnung. (orig.)

  1. Vertical Hole Transport and Carrier Localization in InAs /InAs1 -xSbx Type-II Superlattice Heterojunction Bipolar Transistors

    Science.gov (United States)

    Olson, B. V.; Klem, J. F.; Kadlec, E. A.; Kim, J. K.; Goldflam, M. D.; Hawkins, S. D.; Tauke-Pedretti, A.; Coon, W. T.; Fortune, T. R.; Shaner, E. A.; Flatté, M. E.

    2017-02-01

    Heterojunction bipolar transistors are used to measure vertical hole transport in narrow-band-gap InAs /InAs1 -xSbx type-II superlattices (T2SLs). Vertical hole mobilities (μh) are reported and found to decrease rapidly from 360 cm2/V s at 120 K to approximately 2 cm2/V s at 30 K, providing evidence that holes are confined to localized states near the T2SL valence-miniband edge at low temperatures. Four distinct transport regimes are identified: (1) pure miniband transport, (2) miniband transport degraded by temporary capture of holes in localized states, (3) hopping transport between localized states in a mobility edge, and (4) hopping transport through defect states near the T2SL valence-miniband edge. Region (2) is found to have a thermal activation energy of ɛ2=36 meV corresponding to the energy range of a mobility edge. Region (3) is found to have a thermal activation energy of ɛ3=16 meV corresponding to the hopping transport activation energy. This description of vertical hole transport is analogous to electronic transport observed in disordered amorphous semiconductors displaying Anderson localization. For the T2SL, we postulate that localized states are created by disorder in the group-V alloy of the InAs1 -xSbx hole well causing fluctuations in the T2SL valence-band energy.

  2. Comparison of chemical and nuclear explosions: Numerical simulations of the Non-Proliferation Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kamm, J.R.; Bos, R.J.

    1995-06-01

    In this paper the authors discuss numerical simulations of the Non-Proliferation Experiment (NPE), which was an underground explosion conducted in September 1993 in the volcanic tuff of the Nevada Test Site. The NPE source consisted of 1.29 {times} 10{sup 6} kg of ANFO-emulsion blasting agent, with the approximate energy of 1.1 kt, emplaced 389 m beneath the surface of Rainier Mesa. The authors compare detailed numerical simulations of the NPE with data collected from that experiment, and with calculations of an equally energetic nuclear explosion in identical geology. Calculated waveforms, at ranges out to approximately 1 km, agree moderately well in the time domain with free-field data, and are in qualitative agreement with free-surface records. Comparison of computed waveforms for equally energetic chemical and nuclear sources reveals relatively minor differences beyond the immediate near-source region, with the chemical source having an {approximately}25% greater seismic moment but otherwise indistinguishable (close-in) seismic source properties. 41 refs., 67 figs., 7 tabs.

  3. National independence and nonproliferation in the new states of Central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Gleason, G.

    1993-12-01

    Five independent states emerged in Central Asia from the breakup of the USSR. One of these states, Kazakhstan, possesses nuclear weapons. The other four of these states, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan, are not known to possess nuclear weapons, however they occupy a geostrategic position which makes them important to non-proliferation efforts. The present report profiles the capabilities and intentions of these four Central Asian states. The analysis of capabilities suggests that none of these states has the capability to develop a usable nuclear weapon. However, all of these countries-- especially Uzbekistan--have components of the old Soviet nuclear weapons complex which are now orphans. They have no use for these facilities and must either re-profile them, destroy them, or transfer them. The analysis of intentions suggests that the dynamics of national independence have created a situation in which Uzbekistan has hegemonic designs in the region. Implications for retarding nuclear proliferation in the Central Asian region are examined. Opportunities for outside influence are assessed.

  4. Economic and Non-proliferation Policy Considerations of Uranium Enrichment in Brazil and Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Short, Steven M.; Phillips, Jon R.; Weimar, Mark R.; Mahy, Heidi A.

    2008-09-01

    The nuclear development programs of both Argentina and Brazil have, since the 1970s, been premised on the desire for self-sufficiency and assurance of nuclear fuel supply. While military rivalry and mutual distrust led to nuclear weapons related development programs in the 1970s and 1980s, both countries have since terminated these programs. Furthermore, the governments of both countries have pledged their commitment to exclusively non-explosive use of nuclear energy and have signed the Non Proliferation Treaty (NPT). Utilizing rights provided for under the NPT, both Argentina and Brazil have nuclear fuel production facilities, with the notable exception of enrichment plants, that provide much of the current indigenous fuel requirements for their nuclear power plants. However, both countries are actively developing enrichment capability to fill this gap. The purpose of this report is to assess the economic basis and non-proliferation policy considerations for indigenous enrichment capability within the context of their desired self-sufficiency and to evaluate possible United States Government policy options.

  5. ELASTIC-SCATTERING AND THE CURRENT-VOLTAGE CHARACTERISTICS OF SUPERCONDUCTING NB-INAS-NB JUNCTIONS

    NARCIS (Netherlands)

    VANDERPOST, N; NITTA, J; TAKAYANAGI, H

    1993-01-01

    Superconducting niobium contacts are attached to a 0.8-mum-long epitaxially grown InAs channel sandwiched between insulating InGaAs layers. The current-voltage characteristics show nonlinearities at submultiples of the superconducting energy gap indicative of multiple-Andreev reflections. We demonst

  6. Graphitic platform for self-catalysed InAs nanowires growth by molecular beam epitaxy.

    Science.gov (United States)

    Zhuang, Qian D; Anyebe, Ezekiel A; Sanchez, Ana M; Rajpalke, Mohana K; Veal, Tim D; Zhukov, Alexander; Robinson, Benjamin J; Anderson, Frazer; Kolosov, Oleg; Fal'ko, Vladimir

    2014-01-01

    We report the self-catalysed growth of InAs nanowires (NWs) on graphite thin films using molecular beam epitaxy via a droplet-assisted technique. Through optimising metal droplets, we obtained vertically aligned InAs NWs with highly uniform diameter along their entire length. In comparison with conventional InAs NWs grown on Si (111), the graphite surface led to significant effects on the NWs geometry grown on it, i.e. larger diameter, shorter length with lower number density, which were ascribed to the absence of dangling bonds on the graphite surface. The axial growth rate of the NWs has a strong dependence on growth time, which increases quickly in the beginning then slows down after the NWs reach a length of approximately 0.8 μm. This is attributed to the combined axial growth contributions from the surface impingement and sidewall impingement together with the desorption of adatoms during the diffusion. The growth of InAs NWs on graphite was proposed following a vapour-solid mechanism. High-resolution transmission electron microscopy reveals that the NW has a mixture of pure zinc-blende and wurtzite insertions.

  7. Singularities in magneto-tunneling through InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hapke-Wurst, I.; Zeitler, U.; Haug, R.J. [Hannover Univ. (Germany). Inst. fuer Festkoerperphysik; Frahm, H. [Hannover Univ. (Germany). Inst. fuer Theoretische Physik; Jansen, A.G.M. [Max-Planck-Institut fuer Festkoerperforschung, 38 - Grenoble (France). Hochfeldmagnetlabor; Pierz, K. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2001-04-01

    We have performed magneto-tunneling experiments from three-dimensional electrodes through self-assembled InAs quantum dots. Our measurements show magnetic-field-induced Fermi edge singularities which are strongly enhanced in high magnetic fields. Electrons carrying the majority spin in the emitter show the most pronounced singularities. We compare our experimental results with theoretical calculations. (orig.)

  8. The Origin of Ina: Evidence for Inflated Lava Flows on the Moon

    Science.gov (United States)

    Garry, W. B.; Robinson, M. S.; Zimbelman, J. R.; Bleacher, J. E.; Hawke, B. R.; Crumpler, L. S.; Braden, S. E.; Sato, H.

    2012-01-01

    Ina is an enigmatic volcanic feature on the Moon known for its irregularly shaped mounds, the origin of which has been debated since the Apollo Missions. Three main units are observed on the floor of the depression (2.9 km across, lava flows. Comparison of these unusual lunar mounds and possible terrestrial analogs leads us to hypothesize that features in Ina were formed through lava flow inflation processes. While the source of the lava remains unclear, this new model suggests that as the mounds inflated, breakouts along their margins served as sources for surface flows that created the lower morphologic unit. Over time, mass wasting of both morphologic units has exposed fresh surfaces observed in the blocky unit. Ina is different than the terrestrial analogs presented in this study in that the lunar features formed within a depression, no vent sources are observed, and no cracks are observed on the mounds. However, lava flow inflation processes explain many of the morphologic relationships observed in Ina and are proposed to be analogous with inflated lava flows on Earth.

  9. Temperature dependence of gain and excess noise in InAs electron avalanche photodiodes.

    Science.gov (United States)

    Ker, Pin Jern; David, John P R; Tan, Chee Hing

    2012-12-31

    Measurement and analysis of the temperature dependence of avalanche gain and excess noise in InAs electron avalanche photodiodes (eAPDs) at 77 to 250 K are reported. The avalanche gain, initiated by pure electron injection, was found to reduce with decreasing temperature. However no significant change in the excess noise was measured as the temperature was varied. For avalanche gain > 3, the InAs APDs with 3.5 µm i-region show consistently low excess noise factors between 1.45 and 1.6 at temperatures of 77 to 250 K, confirming that the eAPD characteristics are exhibited in the measured range of electric field. As the dark current drops much more rapidly than the avalanche gain and the excess noise remains very low, our results confirmed that improved signal to noise ratio can be obtained in InAs eAPDs by reducing the operating temperature. The lack of hole impact ionization, as confirmed by the very low excess noise and the exponentially rising avalanche gain, suggests that hole impact ionization enhancement due to band "resonance" does not occur in InAs APDs at the reported temperatures.

  10. InAs Colloidal Quantum Dots Synthesis via Aminopnictogen Precursor Chemistry.

    Science.gov (United States)

    Grigel, Valeriia; Dupont, Dorian; De Nolf, Kim; Hens, Zeger; Tessier, Mickael D

    2016-10-05

    Despite their various potential applications, InAs colloidal quantum dots have attracted considerably less attention than more classical II-VI materials because of their complex syntheses that require hazardous precursors. Recently, amino-phosphine has been introduced as a cheap, easy-to-use and efficient phosphorus precursor to synthesize InP quantum dots. Here, we use aminopnictogen precursors to implement a similar approach for synthesizing InAs quantum dots. We develop a two-step method based on the combination of aminoarsine as the arsenic precursor and aminophosphine as the reducing agent. This results in state-of-the-art InAs quantum dots with respect to the size dispersion and band-gap range. Moreover, we present shell coating procedures that lead to the formation of InAs/ZnS(e) core/shell quantum dots that emit in the infrared region. This innovative synthesis approach can greatly facilitate the research on InAs quantum dots and may lead to synthesis protocols for a wide range of III-V quantum dots.

  11. Atomic resolution imaging of in situ InAs nanowire dissolution at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pennington, R S; Wagner, J B; Boothroyd, C B; Dunin-Borkowski, R E [Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Jinschek, J R, E-mail: robert.pennington@cen.dtu.d [FEI Company, Achtseweg Noord 5, 5600 KA Eindhoven (Netherlands)

    2010-02-01

    We present a preliminary study of the in situ heating of InAs nanowires in a gaseous environment in an environmental transmission electron microscope. Nanowire dissolution, accompanied by dynamic reshaping of crystalline Au-containing catalyst particles at the ends of the wires, is observed, accompanied by indium oxide crystallite formation nearby.

  12. Reconstruction of an InAs nanowire using geometric and algebraic tomography

    DEFF Research Database (Denmark)

    Pennington, Robert S.; König, S.; Alpers, A.;

    2011-01-01

    Geometric tomography and conventional algebraic tomography algorithms are used to reconstruct cross-sections of an InAs nanowire from a tilt series of experimental annular dark-field images. Both algorithms are also applied to a test object to assess what factors affect the reconstruction quality...

  13. Sensing Responses Based on Transfer Characteristics of InAs Nanowire Field-Effect Transistors.

    Science.gov (United States)

    Tseng, Alex C; Lynall, David; Savelyev, Igor; Blumin, Marina; Wang, Shiliang; Ruda, Harry E

    2017-07-16

    Nanowire-based field-effect transistors (FETs) have demonstrated considerable promise for a new generation of chemical and biological sensors. Indium arsenide (InAs), by virtue of its high electron mobility and intrinsic surface accumulation layer of electrons, holds properties beneficial for creating high performance sensors that can be used in applications such as point-of-care testing for patients diagnosed with chronic diseases. Here, we propose devices based on a parallel configuration of InAs nanowires and investigate sensor responses from measurements of conductance over time and FET characteristics. The devices were tested in controlled concentrations of vapour containing acetic acid, 2-butanone and methanol. After adsorption of analyte molecules, trends in the transient current and transfer curves are correlated with the nature of the surface interaction. Specifically, we observed proportionality between acetic acid concentration and relative conductance change, off current and surface charge density extracted from subthreshold behaviour. We suggest the origin of the sensing response to acetic acid as a two-part, reversible acid-base and redox reaction between acetic acid, InAs and its native oxide that forms slow, donor-like states at the nanowire surface. We further describe a simple model that is able to distinguish the occurrence of physical versus chemical adsorption by comparing the values of the extracted surface charge density. These studies demonstrate that InAs nanowires can produce a multitude of sensor responses for the purpose of developing next generation, multi-dimensional sensor applications.

  14. Selective-Area Growth of InAs Nanowires on Ge and Vertical Transistor Application.

    Science.gov (United States)

    Tomioka, Katsuhiro; Izhizaka, Fumiya; Fukui, Takashi

    2015-11-11

    III-V compound semiconductor and Ge are promising channel materials for future low-power and high-performance integrated circuits. A heterogeneous integration of these materials on the same platform, however, raises serious problem owing to a huge mismatch of carrier mobility. We proposed direct integration of perfectly vertically aligned InAs nanowires on Ge as a method for new alternative integrated circuits and demonstrated a high-performance InAs nanowire-vertical surrounding-gate transistor. Virtually 100% yield of vertically aligned InAs nanowires was achieved by controlling the initial surface of Ge and high-quality InAs nanowires were obtained regardless of lattice mismatch (6.7%). The transistor performance showed significantly higher conductivity with good gate control compared to Si-based conventional field-effect transistors: the drain current was 0.65 mA/μm, and the transconductance was 2.2 mS/μm at drain-source voltage of 0.50 V. These demonstrations are a first step for building alternative integrated circuits using vertical III-V/multigate planar Ge FETs.

  15. Prediction of Disease Case Severity Level To Determine INA CBGs Rate

    Science.gov (United States)

    Puspitorini, Sukma; Kusumadewi, Sri; Rosita, Linda

    2017-03-01

    Indonesian Case-Based Groups (INA CBGs) is case-mix payment system using software grouper application. INA CBGs consisting of four digits code where the last digits indicating the severity level of disease cases. Severity level influence by secondary diagnosis (complications and co-morbidity) related to resource intensity level. It is medical resources used to treat a hospitalized patient. Objectives of this research is developing decision support system to predict severity level of disease cases and illustrate INA CBGs rate by using data mining decision tree classification model. Primary diagnosis (DU), first secondary diagnosis (DS 1), and second secondary diagnosis (DS 2) are attributes that used as input of severity level. The training process using C4.5 algorithm and the rules will represent in the IF-THEN form. Credibility of the system analyzed through testing process and confusion matrix present the results. Outcome of this research shows that first secondary diagnosis influence significant to form severity level predicting rules from new disease cases and INA CBGs rate illustration.

  16. Atomic resolution imaging of in situ InAs nanowire dissolution at elevated temperature

    DEFF Research Database (Denmark)

    Pennington, Robert S.; Jinschek, Joerg; Wagner, Jakob Birkedal

    2010-01-01

    We present a preliminary study of the in situ heating of InAs nanowires in a gaseous environment in an environmental transmission electron microscope Nanowire dissolution, accompanied by dynamic reshaping of crystalline Au-containing catalyst particles at the ends of the wires, is observed...

  17. Pathogenic and Ice-Nucleation Active (INA) Bacteria causing Dieback of Willows in Short Rotation Forestry

    Energy Technology Data Exchange (ETDEWEB)

    Nejad, Pajand

    2005-03-01

    To find out whether bacteria isolated from diseased plant parts can be the main causal agent for the dieback appearing in Salix energy forestry plantations in Sweden during the last few years, and if the joint effects of bacteria and frost injury are synergistic, extensive sampling of shoots from diseased Salix plants was performed. We performed several laboratory and greenhouse investigations and used evaluation techniques on the functions of the Ice-Nucleation Active (INA) bacteria. We carried out a comparison between spring and autumn bacterial communities isolated from within (endophytically) and surface (epiphytically) plant tissues of Salix viminalis. Seasonal variation of bacteria in willow clones with different levels of frost sensitivity and symptoms of bacterial damage was also investigated. We further focussed on possible effect of fertilisation and nutrient availability on the bacterial community in relation to plant dieback in Estonian willow plantations. The identification and detection of INA bacteria which cause damage in combination with frost to willow (Salix spp) plants in late fall, winter and spring was performed using BIOLOG MicroPlate, biochemical tests, selective INA primers and 16S rDNA analysis. To distinguish the character for differentiation between these bacteria morphologically and with respect to growing ability different culture media were used. We studied the temperature, at which ice nucleation occurred for individual bacteria, estimated the population of INA bacteria, effect of growth limiting factors, and evaluated the effect of chemical and physical agents for disruption and possible inhibition of INA among individual bacterial strains. The concentration of carbon, nitrogen and phosphorus on INA is discussed. We demonstrate that among the bacterial isolates recovered from the willow plantations, there were many that were capable of ice nucleation at temperatures between -2 and -10 deg C, many that were capable of inducing a

  18. Transcription factor hlh-2/E/Daughterless drives expression of α integrin ina-1 during DTC migration in C. elegans.

    Science.gov (United States)

    Meighan, Christopher M; Kann, Allison P; Egress, Emily R

    2015-09-01

    Integrins are involved in a vast number of cell behaviors due to their roles in adhesion and signaling. The regulation of integrin expression is of particular interest as a mechanism to drive developmental events and for the role of altered integrin expression profiles in cancer. Dynamic regulation of the expression of integrin receptors is required for the migration of the distal tip cell (DTC) during gonadogenesis in Caenorhabditis elegans. α integrin ina-1 is required for DTC motility, yet is up-regulated by an unknown mechanism. Analysis of the promoter for α integrin ina-1 identified two E-box sequences that are required for ina-1 expression in the DTC. Knockdown of transcription factor hlh-2, an established E-box binding partner and ortholog of E/Daughterless, prevented expression of a transcriptional fusion of the ina-1 promoter to RFP and blocked DTC migration. Similarly, knockdown of hlh-2 also prevented expression of a translational fusion of the genomic ina-1 gene to GFP while blocking DTC migration. Knockdown of HLH-2 binding partner MIG-24 also reduced ina-1 expression and DTC migration. Overall, these results show that the transcription factor hlh-2 is required for up-regulation of ina-1 at the onset of DTC migration.

  19. 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.

  20. The Nuclear Non-Proliferation Treaty and the Comprehensive Nuclear-Test-Ban Treaty, the relationship

    Science.gov (United States)

    Graham, Thomas, Jr.

    2014-05-01

    The Nuclear Non-Proliferation Treaty (NPT) is the most important international security arrangement that we have that is protecting the world community and this has been true for many years. But it did not happen by accident, it is a strategic bargain in which 184 states gave up the right forever to acquire the most powerful weapon ever created in exchange for a commitment from the five states allowed to keep nuclear weapons under the NPT (U.S., U.K., Russia, France and China), to share peaceful nuclear technology and to engage in disarmament negotiations aimed at the ultimate elimination of their nuclear stockpiles. The most important part of this is the comprehensive nuclear test ban (CTBT); the thinking by the 184 NPT non-nuclear weapon states was and is that they understand that the elimination of nuclear weapon stockpiles is a long way off, but at least the NPT nuclear weapon states could stop testing the weapons. The CTBT has been ratified by 161 states but by its terms it can only come into force if 44 nuclear potential states ratify; 36 have of the 44 have ratified it, the remaining eight include the United States and seven others, most of whom are in effect waiting for the United States. No state has tested a nuclear weapon-except for complete outlier North Korea-in 15 years. There appears to be no chance that the U.S. Senate will approve the CTBT for ratification in the foreseeable future, but the NPT may not survive without it. Perhaps it is time to consider an interim measure, for the UN Security Council to declare that any future nuclear weapon test any time, anywhere is a "threat to peace and security", in effect a violation of international law, which in today's world it clearly would be.

  1. Surface modifications on InAs decrease indium and arsenic leaching under physiological conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jewett, Scott A. [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); Yoder, Jeffrey A. [Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University of North Carolina-Chapel Hill, Raleigh, NC 27695 (United States); Center for Comparative Medicine and Translational Research, North Carolina State University of North Carolina-Chapel Hill, Raleigh, NC 27695 (United States); Ivanisevic, Albena, E-mail: ivanisevic@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University of North Carolina-Chapel Hill, Raleigh, NC 27695 (United States); Joint Department of Biomedical Engineering North Carolina State University/University of North Carolina-Chapel Hill, Raleigh, NC 27695 (United States)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer InAs was assessed under physiological conditions. Black-Right-Pointing-Pointer A thiol-alcohol and a PEG-based polymer layers demonstrated the highest stability. Black-Right-Pointing-Pointer Unmodified and modified InAs showed no toxicity to zebrafish up to 120 h post fertilization. - Abstract: Devices containing III-V semiconductors such as InAs are increasingly being used in the electronic industry for a variety of optoelectronic applications. Furthermore, the attractive chemical, material, electronic properties make such materials appealing for use in devices designed for biological applications, such as biosensors. However, in biological applications the leaching of toxic materials from these devices could cause harm to cells or tissue. Additionally, after disposal, toxic inorganic materials can leach from devices and buildup in the environment, causing long-term ecological harm. Therefore, the toxicity of these materials along with their stability in physiological conditions are important factors to consider. Surface modifications are one common method of stabilizing semiconductor materials in order to chemically and electronically passivate them. Such surface modifications could also prevent the leaching of toxic materials by preventing the regrowth of the unstable surface oxide layer and by creating an effective barrier between the semiconductor surface and the surrounding environment. In this study, various surface modifications on InAs are developed with the goal of decreasing the leaching of indium and arsenic. The leaching of indium and arsenic from modified substrates was assessed in physiological conditions using inductively coupled plasma mass spectrometry (ICP-MS). Substrates modified with 11-mercapto-1-undecanol (MU) and graft polymerized with poly(ethylene) glycol (PEG) were most effective at preventing indium and arsenic leaching. These surfaces were characterized using contact angle analysis, ellipsometry

  2. Ten-Fold Enhancement of InAs Nanowire Photoluminescence Emission with an InP Passivation Layer.

    Science.gov (United States)

    Jurczak, Pamela; Zhang, Yunyan; Wu, Jiang; Sanchez, Ana M; Aagesen, Martin; Liu, Huiyun

    2017-06-14

    In this Letter, we demonstrate that a significant improvement of optical performance of InAs nanowires can be achieved by capping the core InAs nanowires with a thin InP shell, which successfully passivates the surface states reducing the rate of nonradiative recombination. The improvements have been confirmed by detailed photoluminescence measurements, which showed up to a 10-fold increase in the intensity of room-temperature photoluminescence from the capped InAs/InP nanowires compared to the sample with core-only InAs nanowires. Moreover, the nanowires exhibit a high stability of total photoluminescence emission strength across temperature range from 10 to 300 K as a result of strong quantum confinement. These findings could be the key to successful implementation of InAs nanowires into optoelectronic devices.

  3. In-rich molecular beam epitaxy of InAs on Sb-terminated GaAs(001) surface

    Science.gov (United States)

    Katkov, A. V.; Wang, C. C.; Chi, J. Y.

    2013-05-01

    The effect of various Sb-terminated GaAs(001) templates on the growth of InAs was investigated by varying the As flux. The growth of InAs under In-rich growth conditions on Sb-terminated GaAs(001)-(2×3), (2×4) and (2×8) templates was demonstrated to occur in the Stranski-Krastanov (SK) growth mode, in contrast to the Sb-free case, where the growth process follows the Franck-van der Merwe (FM) growth mechanism. The observed antimony dependent change of growth mode from FM to SK is qualitatively explained by the decrease of the surface energy of the growing InAs layer caused by the segregation of Sb on the surface of the InAs(001).

  4. Use of open source information and commercial satellite imagery for nuclear nonproliferation regime compliance verification by a community of academics

    Science.gov (United States)

    Solodov, Alexander

    The proliferation of nuclear weapons is a great threat to world peace and stability. The question of strengthening the nonproliferation regime has been open for a long period of time. In 1997 the International Atomic Energy Agency (IAEA) Board of Governors (BOG) adopted the Additional Safeguards Protocol. The purpose of the protocol is to enhance the IAEA's ability to detect undeclared production of fissile materials in member states. However, the IAEA does not always have sufficient human and financial resources to accomplish this task. Developed here is a concept for making use of human and technical resources available in academia that could be used to enhance the IAEA's mission. The objective of this research was to study the feasibility of an academic community using commercially or publicly available sources of information and products for the purpose of detecting covert facilities and activities intended for the unlawful acquisition of fissile materials or production of nuclear weapons. In this study, the availability and use of commercial satellite imagery systems, commercial computer codes for satellite imagery analysis, Comprehensive Test Ban Treaty (CTBT) verification International Monitoring System (IMS), publicly available information sources such as watchdog groups and press reports, and Customs Services information were explored. A system for integrating these data sources to form conclusions was also developed. The results proved that publicly and commercially available sources of information and data analysis can be a powerful tool in tracking violations in the international nuclear nonproliferation regime and a framework for implementing these tools in academic community was developed. As a result of this study a formation of an International Nonproliferation Monitoring Academic Community (INMAC) is proposed. This would be an independent organization consisting of academics (faculty, staff and students) from both nuclear weapon states (NWS) and

  5. Nuclear proliferation and civilian nuclear power. Report of the Nonproliferation Alternative Systems Assessment Program. Volume IV. Commercial potential

    Energy Technology Data Exchange (ETDEWEB)

    1980-06-01

    This volume of the Nonproliferation Alternative Systems Assessment Program (NASAP) report provides time and cost estimates for positioning new nuclear power systems for commercial deployment. The assessment also estimates the rates at which the new systems might penetrate the domestic market, assuming the continuing viability of the massive light-water reactor network that now exists worldwide. This assessment does not recommend specific, detailed program plans and budgets for individual systems; however, it is clear from this analysis that any of the systems investigated could be deployed if dictated by national interest.

  6. Structural and electrical properties of catalyst-free Si-doped InAs nanowires formed on Si(111).

    Science.gov (United States)

    Park, Dong Woo; Jeon, Seong Gi; Lee, Cheul-Ro; Lee, Sang Jun; Song, Jae Yong; Kim, Jun Oh; Noh, Sam Kyu; Leem, Jae-Young; Kim, Jin Soo

    2015-11-19

    We report structural and electrical properties of catalyst-free Si-doped InAs nanowires (NWs) formed on Si(111) substrates. The average diameter of Si-doped InAs NWs was almost similar to that of undoped NWs with a slight increase in height. In the previous works, the shape and size of InAs NWs formed on metallic catalysts or patterned structures were significantly changed by introducing dopants. Even though the external shape and size of the Si-doped NWs in this work were not changed, crystal structures inside the NWs were significantly changed. For the undoped InAs NWs, both zincblende (ZB) and wurzite (WZ) structures were observed in transmission-electron microscope images, where the portion of WZ structure was estimated to be more than 30%. However, only ZB was observed with an increase in stacking fault (SF) for the Si-doped NWs. The undoped and Si-doped InAs NWs were used as channels of four-point electrical measurements with Al/Ni electrodes to investigate electrical properties. The resistivity calculated from the current-voltage curve of a Si-doped InAs NW showed 1.32 × 10(-3) Ωcm, which was dramatically decreased from 10.14 × 10(-3) Ωcm for the undoped InAs NW. A relatively low resistivity of catalyst-free Si-doped InAs NWs was achieved without significant change in structural dimensions.

  7. Schottky barrier heights at the interfaces between pure-phase InAs nanowires and metal contacts

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Boyong; Huang, Shaoyun, E-mail: syhuang@pku.edu.cn, E-mail: hqxu@pku.edu.cn; Wang, Jiyin [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Pan, Dong; Zhao, Jianghua [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Xu, H. Q., E-mail: syhuang@pku.edu.cn, E-mail: hqxu@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Division of Solid-State Physics, Lund University, Box 118, S-221 00 Lund (Sweden)

    2016-02-07

    Understanding of the Schottky barriers formed at metal contact-InAs nanowire interfaces is of great importance for the development of high-performance InAs nanowire nanoelectronic and quantum devices. Here, we report a systematical study of InAs nanowire field-effect transistors (FETs) and the Schottky barrier heights formed at the contact-nanowire interfaces. The InAs nanowires employed are grown by molecular beam epitaxy and are high material quality single crystals, and the devices are made by directly contacting the nanowires with a series of metals of different work functions. The fabricated InAs nanowire FET devices are characterized by electrical measurements at different temperatures and the Schottky barrier heights are extracted from the measured temperature and gate-voltage dependences of the channel current. We show that although the work functions of the contact metals are widely spread, the Schottky barrier heights are determined to be distributed over 35–55 meV, showing a weak but not negligible dependence on the metals. The deduced Fermi level in the InAs nanowire channels is found to be in the band gap and very close to the conduction band. The physical origin of the results is discussed in terms of Fermi level pinning by the surface states of the InAs nanowires and a shift in pinned Fermi level induced by the metal-related interface states.

  8. Orientation Dependence of Electromechanical Characteristics of Defect-free InAs Nanowires.

    Science.gov (United States)

    Zheng, Kun; Zhang, Zhi; Hu, Yibin; Chen, Pingping; Lu, Wei; Drennan, John; Han, Xiaodong; Zou, Jin

    2016-03-09

    Understanding the electrical properties of defect-free nanowires with different structures and their responses under deformation are essential for design and applications of nanodevices and strain engineering. In this study, defect-free zinc-blende- and wurtzite-structured InAs nanowires were grown using molecular beam epitaxy, and individual nanowires with different structures and orientations were carefully selected and their electrical properties and electromechanical responses were investigated using an electrical probing system inside a transmission electron microscope. Through our careful experimental design and detailed analyses, we uncovered several extraordinary physical phenomena, such as the electromechanical characteristics are dominated by the nanowire orientation, rather than its crystal structure. Our results provide critical insights into different responses induced by deformation of InAs with different structures, which is important for nanowire-based devices.

  9. In situ surface and interface study of crystalline (3×1)-O on InAs

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Xiaoye, E-mail: xxq102020@utdallas.edu; Wallace, Robert M., E-mail: rmwallace@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States); Wang, Wei-E.; Rodder, Mark S. [Advanced Logic Lab, Samsung Semiconductor, Inc., Austin, Texas 78754 (United States)

    2016-07-25

    The oxidation behavior of de-capped InAs (100) exposed to O{sub 2} gas at different temperatures is investigated in situ with high resolution of monochromatic x-ray photoelectron spectroscopy and low energy electron diffraction. The oxide chemical states and structure change dramatically with the substrate temperature. A (3 × 1) crystalline oxide layer on InAs is generated in a temperature range of 290–330 °C with a coexistence of In{sub 2}O and As{sub 2}O{sub 3}. The stability of the crystalline oxide upon the atomic layer deposition (ALD) of HfO{sub 2} is studied as well. It is found that the generated (3 × 1) crystalline oxide is stable upon ALD HfO{sub 2} growth at 100 °C.

  10. Direct evidence of strain transfer for InAs island growth on compliant Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Marçal, L. A. B.; Magalhães-Paniago, R.; Malachias, Angelo, E-mail: angeloms@fisica.ufmg.br [Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, CEP 31270-901, Belo Horizonte (Brazil); Richard, M.-I. [European Synchrotron (ESRF), ID01 beamline, CS 40220, 38043 Grenoble Cedex 9 (France); Aix-Marseille University, IM2NP-CNRS, Faculté des Sciences de St Jérôme, 13397 Marseille (France); Cavallo, F. [Center for High Technology Materials, University of New Mexico, 1313 Goddard St., Albuquerque, New Mexico 87106 (United States); University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Lagally, M. G. [University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Schmidt, O. G. [Institute for Integrative Nanosciences, IFW-Dresden, D-01171 Dresden (Germany); Schülli, T. Ü. [European Synchrotron (ESRF), ID01 beamline, CS 40220, 38043 Grenoble Cedex 9 (France); Deneke, Ch. [Laboratório Nacional de Nanotecnologia (LNNano/CNPEM), C.P. 6192, CEP 13083-970, Campinas (Brazil)

    2015-04-13

    Semiconductor heteroepitaxy on top of thin compliant layers has been explored as a path to make inorganic electronics mechanically flexible as well as to integrate materials that cannot be grown directly on rigid substrates. Here, we show direct evidences of strain transfer for InAs islands on freestanding Si thin films (7 nm). Synchrotron X-ray diffraction measurements using a beam size of 300 × 700 nm{sup 2} can directly probe the strain status of the compliant substrate underneath deposited islands. Using a recently developed diffraction mapping technique, three-dimensional reciprocal space maps were reconstructed around the Si (004) peak for specific illuminated positions of the sample. The strain retrieved was analyzed using continuous elasticity theory via Finite-element simulations. The comparison of experiment and simulations yields the amount of strain from the InAs islands, which is transferred to the compliant Si thin film.

  11. High speed InAs electron avalanche photodiodes overcome the conventional gain-bandwidth product limit.

    Science.gov (United States)

    Marshall, Andrew R J; Ker, Pin Jern; Krysa, Andrey; David, John P R; Tan, Chee Hing

    2011-11-07

    High bandwidth, uncooled, Indium Arsenide (InAs) electron avalanche photodiodes (e-APDs) with unique and highly desirable characteristics are reported. The e-APDs exhibit a 3dB bandwidth of 3.5 GHz which, unlike that of conventional APDs, is shown not to reduce with increasing avalanche gain. Hence these InAs e-APDs demonstrate a characteristic of theoretically ideal electron only APDs, the absence of a gain-bandwidth product limit. This is important because gain-bandwidth products restrict the maximum exploitable gain in all conventional high bandwidth APDs. Non-limiting gain-bandwidth products up to 580 GHz have been measured on these first high bandwidth e-APDs.

  12. Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots

    Directory of Open Access Journals (Sweden)

    Lin Chien-Hung

    2011-01-01

    Full Text Available Abstract In this report, the influence of the intrinsic transitions between bound-to-delocalized states (crossed states or quasicontinuous density of electron-hole states on photoluminescence excitation (PLE spectra of InAs quantum dots (QDs was investigated. The InAs QDs were different in size, shape, and number of bound states. Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T were compared. Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened. This was attributed to the coupling of the localized QD excited states to the crossed states and scattering of longitudinal acoustical (LA phonons. The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.

  13. Giant Spin-Orbit Splitting in Inverted InAs /GaSb Double Quantum Wells

    Science.gov (United States)

    Nichele, Fabrizio; Kjaergaard, Morten; Suominen, Henri J.; Skolasinski, Rafal; Wimmer, Michael; Nguyen, Binh-Minh; Kiselev, Andrey A.; Yi, Wei; Sokolich, Marko; Manfra, Michael J.; Qu, Fanming; Beukman, Arjan J. A.; Kouwenhoven, Leo P.; Marcus, Charles M.

    2017-01-01

    Transport measurements in inverted InAs /GaSb quantum wells reveal a giant spin-orbit splitting of the energy bands close to the hybridization gap. The splitting results from the interplay of electron-hole mixing and spin-orbit coupling, and can exceed the hybridization gap. We experimentally investigate the band splitting as a function of top gate voltage for both electronlike and holelike states. Unlike conventional, noninverted two-dimensional electron gases, the Fermi energy in InAs /GaSb can cross a single spin-resolved band, resulting in full spin-orbit polarization. In the fully polarized regime we observe exotic transport phenomena such as quantum Hall plateaus evolving in e2/h steps and a nontrivial Berry phase.

  14. Photoreflectance and photoluminescence study of InAs dots-in-a-well nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nedzinskas, Ramūnas; Čechavičius, Bronislovas; Kavaliauskas, Julius; Karpus, Vytautas; Valušis, Gintaras [Semiconductor Physics Institute, Center for Physical Sciences and Technology, A. Goštauto 11, LT-01108 Vilnius (Lithuania); Li, Lianhe; Khanna, Suraj P.; Linfield, Edmund H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2013-12-04

    InAs quantum dots (QDs), embedded within InGaAs/GaAs/AlAs and GaAs/AlAs quantum wells (QWs), are examined by photoreflectance and photoluminescence techniques. Optical properties and electronic structure of two differently designed dots-in-a-well nanostructures is revealed focusing on the effect of strain-reducing InGaAs layer, which is discussed in detail. It is found that the use of InGaAs capping layer red-shifts the QD ground-state interband transition energy by about 100 meV maintaining strong quantization of the electronic states. The changes in InAs QD electronic properties are ascribed mainly to QD size/shape variation due to decomposition of InGaAs layer during growth process.

  15. On the processing of InAs and InSb photodiode applications

    Energy Technology Data Exchange (ETDEWEB)

    Odendaal, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Auret, F.D. [Department of Physics, University of Pretoria, Lynnwood road, Hillcrest, Pretoria 0002 (South Africa)

    2008-07-01

    In this paper, potential methods for the surface passivation of InSb and InAs material, covering both compositional extremes of the promising narrow band gap semiconductor InAsSb, are evaluated. Surface states, mostly due to dangling bonds and exposure to the atmosphere, create generation-recombination centres that negatively influence the dark current, stability, efficiency and related noise characteristics of photosensitive devices fabricated from these materials. The effect of various surface treatments, including sulphuric acid based etching, lactic acid based etching, KOH anodising and Na{sub 2}S anodising, on the relative number of surface states is deduced by evaluating the capacitance versus voltage characteristics of metal-insulator-semiconductor structures fabricated on InAs and InSb. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Coupling of self-assembled InAs quantum dots to surface plasmon polaritons

    DEFF Research Database (Denmark)

    Andersen, Mads Lykke; Stobbe, Søren; Johansen, Jeppe;

    2008-01-01

    InAs quantum dots have been placed at different distances to a silver mirror. We extract the coupling of quantum dots to surface plasmon polaritons as a function of the distance by time-resolved spontaneous emission measurements.......InAs quantum dots have been placed at different distances to a silver mirror. We extract the coupling of quantum dots to surface plasmon polaritons as a function of the distance by time-resolved spontaneous emission measurements....

  17. Surface modifications on InAs decrease indium and arsenic leaching under physiological conditions

    Science.gov (United States)

    Jewett, Scott A.; Yoder, Jeffrey A.; Ivanisevic, Albena

    2012-11-01

    Devices containing III-V semiconductors such as InAs are increasingly being used in the electronic industry for a variety of optoelectronic applications. Furthermore, the attractive chemical, material, electronic properties make such materials appealing for use in devices designed for biological applications, such as biosensors. However, in biological applications the leaching of toxic materials from these devices could cause harm to cells or tissue. Additionally, after disposal, toxic inorganic materials can leach from devices and buildup in the environment, causing long-term ecological harm. Therefore, the toxicity of these materials along with their stability in physiological conditions are important factors to consider. Surface modifications are one common method of stabilizing semiconductor materials in order to chemically and electronically passivate them. Such surface modifications could also prevent the leaching of toxic materials by preventing the regrowth of the unstable surface oxide layer and by creating an effective barrier between the semiconductor surface and the surrounding environment. In this study, various surface modifications on InAs are developed with the goal of decreasing the leaching of indium and arsenic. The leaching of indium and arsenic from modified substrates was assessed in physiological conditions using inductively coupled plasma mass spectrometry (ICP-MS). Substrates modified with 11-mercapto-1-undecanol (MU) and graft polymerized with poly(ethylene) glycol (PEG) were most effective at preventing indium and arsenic leaching. These surfaces were characterized using contact angle analysis, ellipsometry, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Substrates modified with collagen and synthetic polyelectrolytes were least effective, due to the destructive nature of acidic environments on InAs. The toxicity of modified and unmodified InAs, along with raw indium, arsenic, and PEG components was assessed

  18. Broadening of length distributions of Au-catalyzed InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Berdnikov, Yury, E-mail: yuryberdnikov@gmail.com [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); Sibirev, Nikolay [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); St. Petersburg State Polytechnical University, 195251 St-Petersburg (Russian Federation); Schmidtbauer, Jan [Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany); Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund (Sweden); Borg, Mattias [Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund (Sweden); IBM Research – Zurich, Säumerstrasse 4, 8803 Rüschlikon (Switzerland); Johansson, Jonas [Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund (Sweden); Dubrovskii, Vladimir [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); St. Petersburg State University, Physical Faculty, Ulianovskaya Street 3, Petrodvorets, 198504 St. Petersburg (Russian Federation); ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg (Russian Federation)

    2016-06-17

    We investigate kinetic broadening effects on the length distributions of gold-catalyzed InAs nanowires having different diameters. It is shown that the length distributions acquire bimodal shape when the longest nanowires exceed the diffusion length of indium adatoms on the nanowire sidewalls. Later on, the length distributions recover unimodal shapes. We develop a theoretical model that is capable of describing the observed behaviors by accounting for the diffusion-induced character of the vapor-liquid-solid growth.

  19. Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Becker, K.; Brau, C.A. [Vanderbilt Univ., Nashville, TN (United States)

    1995-12-31

    Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.

  20. Single-Photon Emission from a Single InAs Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    DOU Xiu-Ming; SUN Bao-Quan; HUANG She-Song; NI Hai-Qiao; NIU Zhi-Chuan

    2008-01-01

    Excitation power-dependent micro-photoluminescence spectra and photon-correlation measurement are used to study the optical properties and photon statistics of single InAs quantum dots.Exciton and biexciton emissions,whose photoluminescence intensities have linear and quadratic excitation power dependences,respectively,are identified.Under pulsed laser excitation,the zero time delay peak of second order correlation function corresponding to exciton emission is well suppressed,which is a clear evidence of single photon emission.

  1. Organic Scintillators in Nonproliferation Applications With a Hybridized Double-Pulse Rejection Technique

    Science.gov (United States)

    Bourne, Mark Mitchell

    Alternative detection technologies are crucial to meeting demand for neutron detectors, for the current production of He-3, which has been the classical neutron choice, is insufficient. Organic scintillators are a strong candidate as a He-3 alternative due to their high efficiency, fast timing properties, and capabilities for separately identifying gamma-rays and neutrons through pulse shape discrimination (PSD). However, the use of organic scintillators in environments with numerous gamma rays can be limited because overlapping gamma-ray events can be misclassified as neutron events during PSD. To solve this problem, a new, hybridized double-pulse cleaning technique, consisting of three separate cleaning algorithms, was developed. The technique removes gamma-ray double pulses while preserving as many neutron pulses as possible. This technique was applied to separate experiments of Cf-252 and a gamma-ray source when measuring at a 100-kHz count rate and a field of 1000 incident gamma rays per incident neutron. It was found that stilbene scintillators were capable of intrinsic neutron efficiencies between 15-19% when measuring bare Cf-252 and 13-17% when exposed to the gamma-ray field. Misclassification rates ranged from 10-6-10-5, a factor-of-5 better than both the EJ-309 liquid and BB3-5 plastic. Next, plutonium experiments were performed with stilbene to determine which cleaning algorithm was best for each sample. A clear correlation was found that related the correct method of cleaning to the measured gamma ray-to-neutron ratio. When the measured gamma ray-to-neutron ratio is 10 or below, the template cleaning algorithm is preferred, while the fractional and hybrid cleaning algorithms are preferred when the gamma ray-to-neutron ratio is 100 or greater. Discriminating neutron sources such as Cf-252 or AmLi from SNM samples such as plutonium is a top priority in nonproliferation. We demonstrate that time-correlated experiments, utilizing both PSD-capable plastic

  2. Electrical Property of Infrared-Sensitive InAs Solar Cells

    Institute of Scientific and Technical Information of China (English)

    DENG Hui-Yong; WANG Qi-Wei; TAO Jun-Chao; WU Jie; HU Shu-Hong; CHEN Xin; DAI Ning

    2010-01-01

    @@ InAs infrared-sensitive solar cells are fabricated by using the films grown by the liquid phase epitaxy technique.The film microstructures are characterized by x-ray diffraction and scanning electronic microscopy.The currentvoltage characteristics of the solar cells in the dark and under AM1.5 illumination at 300 K and 77K are discussed.The conversion efficiency of p-InAs/n-sub InAs cells decreases when the thickness of the p-type film changes from 1.7μm to 3.5μm,which is caused by the reduced effective photons near p-n junction.The p-InAs/n-InAs/n-sub InAs solar cell with the conversion efficiency of 7.43% in 1-2.5μm under AM1.5 at 77K is obtained.The short circuit current density increases dramatically with decreasing temperature due to the weakened effect of phonon scattering.

  3. Geometric factors in the magnetoresistance of n-doped InAs epilayers

    KAUST Repository

    Sun, Jian

    2013-11-27

    We investigate the magnetoresistance (MR) effect in n-doped InAs and InAs/metal hybrid devices with geometries tailored to elucidate the physical mechanism and the role of geometry in the MR. Despite the isotropic Fermi surface in InAs, we observe a strong intrinsic MR in the InAs epilayer due to the existence of a surface conducting layer. Experimental comparison confirms that the extraordinary MR in the InAs/metal hybrids outperforms the orbital MR in the Corbino disk in terms of both the MR ratio and the magnetic field resolution. The results also indicate the advantage of a two-contact configuration in the hybrid devices over a four-contact one with respect to the magnetic field resolution. This is in contrast to previously reported results, where performance was evaluated in terms of the MR ratio and a four-contact configuration was found to be optimal. By applying Kohler\\'s rule, we find that at temperatures above 75 K the extraordinary MR violates Kohler\\'s rule, due to multiple relaxation rates, whereas the orbital MR obeys it. This finding can be used to distinguish the two geometric effects, the extraordinary MR and the orbital MR, from each other.

  4. Report of a workshop on nuclear forces and nonproliferation Woodrow Wilson international center for scholars, Washington, DC October 28, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Pilat, Joseph F [Los Alamos National Laboratory

    2010-12-08

    A workshop sponsored by the Los Alamos National Laboratory in cooperation with the Woodrow Wilson International Center for Scholars was held at the Wilson Center in Washington, DC, on October 28, 2010. The workshop addressed evolving nuclear forces and their impacts on nonproliferation in the context of the new strategic environment, the Obama Administration's Nuclear Posture Review and the 2010 NPT Review Conference. The discussions reflected the importance of the NPR for defining the role of US nuclear forces in dealing with 21st century threats and providing guidance for National Nuclear Security Administration (NNSA) and Department of Defense (DoD) programs and, for many but not all participants, highlighted its role in the successful outcome of the NPT RevCon. There was widespread support for the NPR and its role in developing the foundations for a sustainable nuclear-weapon program that addresses nuclear weapons, infrastructure and expertise in the broader nonproliferation, disarmament and international security contexts. However, some participants raised concerns about its implementation and its long-term effectiveness and sustainability.

  5. Review and comment on the advanced spent fuel management process (1): Technical aspects and non-proliferation concerns

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yo Taik

    2001-01-01

    Efforts are made to analyze the project, the Advanced Spent Fuel Management Technology (ASFMT), which is currently carried out at Korea Atomic Energy Research Institute, on the technical feasibility and validity as well as on the nuclear non-proliferation concerns. The project is a part of a program under the 'Long and Midterm Nuclear Development Program'. On the technical analysis, reviewed the papers presented at the national and international meetings on the subject by KAERI staffs, and also participated to various technical discussions on the 'Mock-up Test', currently in progress. On the non-proliferation concerns, the ASFMT project was reviewed and analyzed in reference to various programs currently in progress or in a formulation stages in US, such as the DOE TOPS and ATW. Further reviewed the past JASNEC process and programs for possible application of the ASFMT project for JASNEC project. Provided a few thoughts for effectively carrying out the ASFMT project, and a plan for the next phase is presented.

  6. Supporting the President's Arms Control and Nonproliferation Agenda: Transparency and Verification for Nuclear Arms Reductions

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, James E [Los Alamos National Laboratory; Meek, Elizabeth [Los Alamos National Laboratory

    2009-01-01

    The President's arms control and nonproliferation agenda is still evolving and the details of initiatives supporting it remain undefined. This means that DOE, NNSA, NA-20, NA-24 and the national laboratories can help define the agenda, and the policies and the initiatives to support it. This will require effective internal and interagency coordination. The arms control and nonproliferation agenda is broad and includes the path-breaking goal of creating conditions for the elimination of nuclear weapons. Responsibility for various elements of the agenda will be widely scattered across the interagency. Therefore an interagency mapping exercise should be performed to identify the key points of engagement within NNSA and other agencies for creating effective policy coordination mechanisms. These can include informal networks, working groups, coordinating committees, interagency task forces, etc. It will be important for NA-20 and NA-24 to get a seat at the table and a functional role in many of these coordinating bodies. The arms control and nonproliferation agenda comprises both mature and developing policy initiatives. The more mature elements such as CTBT ratification and a follow-on strategic nuclear arms treaty with Russia have defined milestones. However, recent press reports indicate that even the START follow-on strategic arms pact that is planned to be complete by the end of 2009 may take significantly longer and be more expansive in scope. The Russians called for proposals to count non-deployed as well as deployed warheads. Other elements of the agenda such as FMCT, future bilateral nuclear arms reductions following a START follow-on treaty, nuclear posture changes, preparations for an international nuclear security summit, strengthened international safeguards and multilateral verification are in much earlier stages of development. For this reason any survey of arms control capabilities within the USG should be structured to address potential needs

  7. Nonproliferation, arms control and disarmament and extended deterrence in the new security environment

    Energy Technology Data Exchange (ETDEWEB)

    Pilat, Joseph F [Los Alamos National Laboratory

    2009-01-01

    other activities are important in themselves, and are essential to maintaining and strengthening the Nonproliferation Treaty (NPT) bargain by bolstering two of its pillars - nonproliferation and peaceful nuclear energy cooperation. There is no alternative, and little prospect for a better deal.

  8. 76 FR 14419 - Exercise of Authority Under Section 212(d)(3)(B)(i) of the Immigration and Nationality Act

    Science.gov (United States)

    2011-03-16

    ... SECURITY Office of the Secretary Exercise of Authority Under Section 212(d)(3)(B)(i) of the Immigration and...(d)(3)(B)(i) of the Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as.... Citizenship and Immigration Services (USCIS), in consultation with U.S. Immigration and Customs...

  9. 76 FR 14418 - Exercise of Authority Under Section 212(d)(3)(B)(i) of the Immigration and Nationality Act

    Science.gov (United States)

    2011-03-16

    ... SECURITY Office of the Secretary Exercise of Authority Under Section 212(d)(3)(B)(i) of the Immigration and...(d)(3)(B)(i) of the Immigration and Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended, as... determination will be made by U.S. Citizenship and Immigration Services (USCIS), in consultation with...

  10. 77 FR 41795 - Exercise of Authority Under Section 212(d)(3)(B)(i) of the Immigration and Nationality Act

    Science.gov (United States)

    2012-07-16

    ... SECURITY Office of the Secretary Exercise of Authority Under Section 212(d)(3)(B)(i) of the Immigration and...(d)(3)(B)(i) of the Immigration and ] Nationality Act (INA), 8 U.S.C. 1182(d)(3)(B)(i), as amended.... Implementation of this determination will be made by U.S. Citizenship and Immigration Services (USCIS),...

  11. NASAP: a computer code for the evaluation of the Non-proliferation Alternative Systems Assessment Program concepts. Final report in support of Task 2. [PWR; BWR

    Energy Technology Data Exchange (ETDEWEB)

    Maul, B.A.

    1979-09-01

    The Non-Proliferation Alternative Systems Assessment Program (NASAP) computer code was developed to calculate the LWR and NASAP choice reactor cost through an arbitrary year T/sub N/. The final cost is arrived at by calculation of cost contributory factors for both LWR and NASAP choice reactors.

  12. Demonstrating Predictive Confidence for a Paradigm Dissolver Model Using Methods for Evaluating Higher Order Moments: A “Case Study” for Nuclear Nonproliferation

    OpenAIRE

    Peltz, James J.

    2016-01-01

    This dissertation performs sensitivity analysis, uncertainty quantification up to 3rd-order (including covariance and skewness), and forward and inverse predictive modeling for a dissolver model of interest to nonproliferation. The original results presented in this dissertation highlight the effects of uncertainties which necessarily characterize measurements and computations, and the reduction in the predicted uncertainties by combining optimally the experimental and computational information.

  13. Leveraging U.S. nuclear weapons policy to advance U.S. nonproliferation goals : implications of major theories of international relations.

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Andrew

    2009-06-01

    National policymakers are currently considering a dilemma of critical importance to the continued security of the United States: how can U.S. nuclear weapons policies be leveraged to benefit U.S. nuclear nonproliferation goals in the near-term, without sacrificing U.S. national security? In its role supporting U.S. nuclear weapons policy, Sandia National Laboratories has a responsibility to provide objective technical advice to support policy deliberations on this question. However, to best fulfill this duty Sandia must have a broader understanding of the context of the problem. To help develop this understanding, this paper analyzes the two predominant analytical perspectives of international relations theory to explore their prescriptions for how nuclear weapons and nonproliferation policies interact. As lenses with which to view and make sense of the world, theories of international relations must play a crucial role in framing the trade-offs at the intersection of the nuclear weapons and nonproliferation policy domains. An analysis of what these theories suggest as courses of action to leverage nuclear weapons policies to benefit nonproliferation goals is then offered, with particular emphasis on where the policy prescriptions resulting from the respective theories align to offer near-term policy changes with broad theoretical support. These policy prescriptions are then compared to the 2001 Nuclear Posture Review to understand what the theories indicate policymakers may have gotten right in their dealing with the nuclear dilemma, and where they may have gone wrong. Finally, a brief international relations research agenda is proposed to help address the dilemma between nuclear deterrence and nuclear nonproliferation policies, with particular emphasis on how such an agenda can best support the needs of the policy community and a potential 'all things nuclear' policy deliberation and decision-support framework.

  14. MBE - growth of self-assembled uncapped InAs quantum dots on GaAs (001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Jost, Thomas; Haug, Rolf J. [Institut fuer Festkoerperphysik, Abteilung Nanostrukturen, Leibniz Universitaet Hannover (Germany); Rugeramigabo, Eddy P. [Institut fuer Festkoerperphysik, Abteilung Nanostrukturen, Leibniz Universitaet Hannover (Germany); QUEST Centre for Quantum Engineering and Space-Time Research, Leibniz Universitaet Hannover (Germany)

    2013-07-01

    InAs quantum dots (QDs) are well known nanostructures which can be grown by molecular beam epitaxy (MBE). The electronic properties of an InAs QD depend on the form, external fields and the charges accumulated in the dot. For self-assembled uncapped InAs QDs we have studied the growth conditions to get well defined and reproducible parameters of QDs like: diameter, density of QDs and inter-dot distance. To produce the InAs QDs we have grown two monolayers of InAs on a GaAs (001) surface under different conditions. We have shown that the density and inter-dot distance of QDs depends on the growth-rate and the annealing. The diameter of the QDs showed a dependence on annealing. Now we are able to produce QDs with a diameter of 50 nm, inter-dot distance of 70 nm and a density of around 2.10{sup 10} QDs/cm{sup 2}, which will be used in transport experiments.

  15. Characterization of the inaA gene and expression of ice nucleation phenotype in Pantoea ananatis isolates from Maize White Spot disease.

    Science.gov (United States)

    Miller, A M; Figueiredo, J E F; Linde, G A; Colauto, N B; Paccola-Meirelles, L D

    2016-03-04

    Maize White Spot (MWS), a foliar disease caused by Pantoea ananatis, could cause up to 60% yield loss. Some strains of P. ananatis harboring the ice nucleation gene inaA catalyze the formation of ice nuclei, causing tissue damage at temperatures slightly below freezing. Little is known about the relationship between the presence of the ina gene in this maize pathogen and its expression during the phenomenon of ice nucleus formation. Here, we attempted to verify the presence of the inaA gene and the expression of phenotype in vitro. The identity of the isolates and the presence of the inaA gene were determined by P. ananatis species-specific primers. The expression of the inaA gene was assessed in vitro by the visualization of ice-crystal formation in water at subzero temperatures. A total of ninety P. ananatis isolates from MWS lesions were characterized. The presence of the inaA gene was confirmed by gel electrophoresis of the 350-400-bp PCR products. The inaA primers did not lead to DNA fragment amplification in three isolates. The ice nucleation phenotype was expressed in 83.34% of the isolates carrying the inaA gene. Our study showed that the ice nucleation in P. ananatis isolated from MWS lesions was dependent on the presence of a functional ina gene in the genome. We also found evidence indicating that some P. ananatis strains have a mutated form of the inaA gene, producing a non-functional ice nucleation protein. This is the first report on inaA gene characterization in P. ananatis isolates from Maize White Spot.

  16. Nuclear non-proliferation: the U.S. obligation to accept spent fuel from foreign research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Shapar, Howard K.; Egan, Joseph R. [Shaw, Pittman, Potts and Trowbridge (United States)

    1995-12-31

    The U.S. Department of Energy (DOE) had a 35-year program for the sale and receipt (for reprocessing) of high-enriched research reactor fuel for foreign research reactors, executed pursuant to bilateral agreements with nuclear trading partners. In 1988, DOE abruptly let this program lapse, citing environmental obstacles. DOE promised to renew the program upon completion of an environmental review which was to take approximately six months. After three and a half years, an environmental assessment was finally produced.Over a year and half elapsed since publication of the assessment before DOE finally took action to renew the program. The paper sets forth the nuclear non-proliferation and related foreign policy considerations which support renewal of the program. It also summarized the contractual and other commitments made to foreign research reactors and foreign governments and aspects of U.S. environmental law as they apply to continuation of the program. (author).

  17. [Immunohistochemical study of human breast tumors using monoclonal antibodies to intermediate filament proteins (nonproliferating epithelial structures in breast dysplasia)].

    Science.gov (United States)

    Gel'shteĭn, V I; Chipysheva, T A; Litvinova, L V; Ermilova, V D; Bannikov, G A

    1985-01-01

    An immunohistochemical analysis of nonproliferating epithelial structures was carried out in 10 samples of human breast dysplasia and in 4 samples of tissue surrounding mammary gland carcinoma. Monoclonal mouse antibodies against individual prekeratins of rat monolayer epithelial antibodies of clone C12 against rat prekeratin with the molecular mass 49 kilodalton and antibodies of clone E3 against rat prekeratin with the molecular mass 40 kilodalton-monoclonal antibodies against vimentin (clone 30), as well as polyclonal antibodies against smooth muscle myosin and against the basement membrane glycoprotein laminin were used. The lining epithelium of all glandular structures reacted only with C12 antibodies. Two variants of myoepithelial cells containing myosin were detected. Variant I contains myosin and vimentin and is localized in intralobular ducts. Variant 2 contains myosin and prekeratin, recognized by E3 antibodies and is found in extralobular ducts.

  18. The fight against international terrorism and changes in the U.S. nuclear non-proliferation and disarmament strategy

    Directory of Open Access Journals (Sweden)

    Inmaculada Marrero Rocha

    2003-12-01

    Full Text Available This article examines how the the fight against international terrorism, as a new organising principle in U.S. foreign policy and security policy, has conditioned and modified the American conception of and strategy for combatting nuclear arms proliferation. On the one hand, it analyses the concepts of “axis of evil” or “rogue states” as instruments of automatic and forced connection between international terrorism and nuclear armsproliferating states. On the other hand, it also deals with the changes in American nonproliferation and disarmament strategy, characterised by a distrust towards international cooperation and a clear preference for using means of a unilateral nature, which challenge, and even scorn, international institutions and the rules of international law in this area.

  19. Nuclear proliferation and civilian nuclear power: report of the Nonproliferation Alternative Systems Assessment Program. Volume 1. Program summary

    Energy Technology Data Exchange (ETDEWEB)

    1979-12-01

    This report summarizes the Nonproliferation Alternative Systems Assessment Program (NASAP): its background, its studies, and its results. This introductory chapter traces the growth of the issue of nuclear weapons proliferation and the organization and objectives of NASAP. Chapter 2 summarizes the program's assessments, findings and recommendations. Each of Volumes II-VII reports on an individual assessment (Volume II: Proliferation Resistance; Volume III: Resources and Fuel Cycle Facilities; Volume IV: Commercial Potential; Volume V: Economics and Systems Analysis; Volume VI: Safety and Environmental Considerations for Licensing; Volume VII: International Perspectives). Volume VIII (Advanced Concepts) presents a combined assessment of several less fully developed concepts, and Volume IX (Reactor and Fuel Cycle Descriptions) provides detailed descriptions of the reactor and fuel-cycle systems studied by NASAP.

  20. THE ROLE AND RATIONALE OF THE NUCLEAR NON-PROLIFERATION TREATY IN THE TWENTY-FIRST CENTURY

    Directory of Open Access Journals (Sweden)

    Tom COPPEN

    2012-12-01

    Full Text Available Much has been written about perceived weaknesses of the NPT and the challenges it has been facing over the last decades. Analysing the most important provisions of the NPT, this article demonstrates how the treaty has managed to maintain its central role in the non-proliferation regime since its conclusion, and how it retains enough flexibility within its review mechanism and its managerial approach to supervision to keep this position for the decades to come. The theoretical framework of the article is formed by theory of arms control law, relevant features of which are: a large influence of politics and national interests of states on the rule of law; its flexible yet treaty-based nature; and the distinctive role of supervision in order to ensure compliance with primary rules. The article analyses key NPT provisions. Based on Article VIII, the NPT Review Conferences have both an important political and legal function. They are the NPT’s mechanism for review, implementation and supervision; in legal terms, they enable the evolution of the NPT based on subsequent agreement and practice. The NPT articles on non-proliferation and disarmament illustrate how the NPT has evolved to close off loopholes (Articles I and II and retains its flexibility whilst providing a global platform for negotiations on nuclear disarmament (Article VI. Article III evolved and must be understood to oblige NPT states to sign an Additional Protocol (AP with the IAEA. Article IV sets the parameters for the peaceful uses of nuclear energy, but leaves room for negotiation and conflict. The supervision of the NPT, illustrated by the case of Iran, is a complicated process involving international organisations such as the IAEA and the UNSC; while these may play important roles, however, the enforcement of the NPT is ultimately left to the NPT states themselves.

  1. TOWARDS FULFILLMENT OF FUNDAMENTAL RULES OF HUMANITARIAN LAW IN THE CONTEXT OF THE NUCLEAR NON-PROLIFERATION TREATY

    Directory of Open Access Journals (Sweden)

    s. Bagheri

    2016-01-01

    Full Text Available The Non-Proliferation Treaty (NPT is an international treaty that should be implemented during both peace and wartime. However, the obligations included in the treaty are dependent upon states' attitudes regarding other issues. Non-use of nuclear weapons is directly related to negotiations done for the purpose of non-proliferation of nuclear weapons, non-production or accumulation by other means and disarmament. In our day, prevention of the proliferation of nuclear weapons has been one of the issues of international law.The present study is of crucial significance due to its endeavor to clarify the general principles of Humanitarian Law in a relationship to the threat of nuclear weapons' up to now, a special norm; significantly limiting or completely prohibiting the use of nuclear weapons, has not been accepted in international law. However, customary international humanitarian law regarding the use of nuclear weapons holds great value because of its purpose in eliminating nuclear weapons as a means of war through ascertaining their non-use and also appeasing the importance of nuclear ascendancy. In this respect, the NPT regime and its relationship with international humanitarian law will be discussed. Firstly, the NPT background, formation, main objectives and principles will be analyzed. In order to evaluate the relationship between the NPT and humanitarian law, the humanitarian obligations in general, humanitarian obligations in the context of the NPT and fulfillmen t of these obligations under the NPT should be studied. One of the main parts of the study is nuclear disarmament obligation included in the NPT. In this section, nuclear disarmament obligation in the context of the NPT and the legal framework of possible, general and comprehensive disarmament will be examined.

  2. Temperature dependence of the lowest excitonic transition for an InAs ultrathin quantum well

    Science.gov (United States)

    Singh, S. D.; Porwal, S.; Sharma, T. K.; Rustagi, K. C.

    2006-03-01

    Temperature dependent photoluminescence and photoreflectance techniques are used to investigate the lowest excitonic transition of InAs ultrathin quantum well. It is shown that the temperature dependence of the lowest energy transition follows the band gap variation of GaAs barrier, which is well reproduced by calculated results based on the envelope function approximation with significant corrections due to strain and temperature dependences of the confinement potential. A redshift in photoluminescence peak energy compared to photoreflectance is observed at low temperatures. This is interpreted to show that the photoluminescence signal originates from the recombination of carriers occupying the band-tail states below the lowest critical point.

  3. Temperature-dependent energy band gap variation in self-organized InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Inah [CEA/CNRS/UJF Joint Team ' ' Nanophysics and Semiconductors,' ' Institut Neel-CNRS, BP 166, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France); Dong Song, Jin; Lee, Jungil [Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2011-10-10

    We investigated the temperature-dependent variation of the photoluminescence emission energy of self-organized InAs/GaAs quantum dots (QDs) grown by conventional Stranski-Krastanov (SK) molecular beam epitaxy and migration-enhanced molecular beam epitaxy (MEMBE) and that of MEMBE InAs QDs in a symmetric and an asymmetric In{sub 0.2}Ga{sub 0.8}As/GaAs well. The temperature-dependent energy variation of each QD is analyzed in low and high temperature regions, including a sigmoidal behavior of conventional SK quantum dots with the well-known Varshni and semi-empirical Fan models.

  4. Spin dynamics and hyperfine interaction in InAs semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Eble, B.; Krebs, O.; Voisin, P.; Lemaitre, A.; Kudelski, A. [CNRS - Laboratoire de Photonique et Nanostructures, Route de Nozay, 91460 Marcoussis (France); Braun, P.F.; Lombez, L.; Marie, X.; Urbaszek, B.; Amand, T.; Lagarde, D.; Renucci, P. [Laboratoire de Nanophysique Magnetisme et Optoelectronique, INSA, 31077 Toulouse Cedex 4 (France); Kowalik, K. [CNRS - Laboratoire de Photonique et Nanostructures, Route de Nozay, 91460 Marcoussis (France); Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw (Poland); Kalevich, V.K.; Kavokin, K.V. [Ioffe Institute, Politekhnicheskaya 26, St-Petersburg 194021 (Russian Federation)

    2006-08-15

    We present a detailed study of the hyperfine interaction between carrier and nuclear spins in InAs semiconductor quantum dots. Time resolved measurements on excitons in positively charged quantum dots show the electron spin relaxation due to random fluctuations of the spin orientation of the nuclei in the quantum dot. A complimentary aspect of the hyperfine interaction can be uncovered in single dot continuous wave photoluminescence experiments in a weak magnetic field, namely the Overhauser shift due to the dynamic polarisation of the nuclei following excitation with circularly polarised light. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Anomalous photoconductive behavior of a single InAs nanowire photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Li, Junshuai; Yan, Xin; Sun, Fukuan; Zhang, Xia, E-mail: xzhang@bupt.edu.cn; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2015-12-28

    We report on a bare InAs nanowire photodetector which exhibits an anomalous photoconductive behavior. Under low-power illumination, the current is smaller than the dark current, and monotonously decreases as the excitation power increases. When the excitation power is high enough, the current starts to increase normally. The phenomenon is attributed to different electron mobilities in the “core” and “shell” of a relatively thick nanowire originating from the surface effect, which result in a quickly dropped “core current” and slowly increased “shell current” under illumination.

  6. Unit Cell Structure of Crystal Polytypes in InAs and InSb Nanowires

    DEFF Research Database (Denmark)

    Kriegner, Dominik; Panse, Christian; Mandl, Bernhard

    2011-01-01

    , wurtzite, and 4H polytypes for InAs and InSb nanowires, using X-ray diffraction and transmission electron microscopy. The results are compared to density functional theory calculations. Experiment and theory show that the occurrence of hexagonal bilayers tends to stretch the distances of atomic layers...... parallel to the c axis and to reduce the in-plane distances compared to those in zinc blende. The change of the lattice parameters scales linearly with the hexagonality of the polytype, defined as the fraction of bilayers with hexagonal character within one unit cell....

  7. Spin Relaxation of Electrons in Single InAs Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    MA Shan-Shan; DOU Xiu-Ming; CHANG Xiu-Ying; SUN Bao-Quan; XIONG Yong-Hua; NIU Zhi-Chuan; NI Hai-Qiao

    2009-01-01

    By using polarization-resolved photoluminescence spectra, we study the electron spin relaxation in single InAs quantum dots (QDs) with the configuration of positively charged excitons X~+ (one electron, two holes). The spin relaxation rate of the hot electrons increases with the increasing energy of exciting photons. For electrons localized in QDs the spin relaxation is induced by hyperfine interaction with the nuclei. A rapid decrease of polarization degree with increasing temperature suggests that the spin relaxation mechanisms are mainly changed from the hyperfine interaction with nuclei into an electron-hole exchange interaction.

  8. Making Mn substitutional impurities in InAs using a scanning tunneling microscope.

    Science.gov (United States)

    Song, Young Jae; Erwin, Steven C; Rutter, Gregory M; First, Phillip N; Zhitenev, Nikolai B; Stroscio, Joseph A

    2009-12-01

    We describe in detail an atom-by-atom exchange manipulation technique using a scanning tunneling microscope probe. As-deposited Mn adatoms (Mn(ad)) are exchanged one-by-one with surface In atoms (In(su)) to create a Mn surface-substitutional (Mn(In)) and an exchanged In adatom (In(ad)) by an electron tunneling induced reaction Mn(ad) + In(su) --> Mn(In) + In(ad) on the InAs(110) surface. In combination with density-functional theory and high resolution scanning tunneling microscopy imaging, we have identified the reaction pathway for the Mn and In atom exchange.

  9. Optical control of electron spin qubit in InAs self-assembled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Emary, Clive [TU Berlin, Sekr. PN 7-1, Institut fuer Theoretische Physik, Hardenbergstr. 36, D-10623 Berlin (Germany); Sham, Lu Jeu [Department of Physics, University of California San Diego, La Jolla, California 92093 (United States)

    2008-07-01

    The spin of an electron trapped in a self-assembled quantum dot is viewed as a promising quantum bit. We present here a theory of the control of such qubits using short laser pulses to excite virtual trion states within the dots. We describe mechanisms for qubit initialisation and for performing universal one and two qubit operations. We show that, for InAs dots, initialisation can be achieved on the nanosecond time-scale, and that coherent operations can performed with laser pulses with durations of tens of picoseconds. These results are of direct relevance to current experiments.

  10. Quantum efficiency and oscillator strength of site-controlled InAs quantum dots

    DEFF Research Database (Denmark)

    Albert, F.; Stobbe, Søren; Schneider, C.

    2010-01-01

    We report on time-resolved photoluminescence spectroscopy to determine the oscillator strength (OS) and the quantum efficiency (QE) of site-controlled InAs quantum dots nucleating on patterned nanoholes. These two quantities are determined by measurements on site-controlled quantum dot (SCQD......) samples with varying thickness of the capping layer. We determine radiative and nonradiative decay rates, from which we calculate an OS of 10.1+/-2.6 and an encouragingly high QE of (47+/-14)% for the SCQDs. The nonideal QE is attributed to nonradiative recombination at the etched nanohole interface...

  11. Symmetry breaking of ionic semiconductors under pressure: the case of InAs

    Energy Technology Data Exchange (ETDEWEB)

    Libotte, H; Gaspard, J P [Condensed Matter Physics Laboratory, University of Liege, B5, B-4000 Sart-Tilman (Belgium); Aquilanti, G; Pascarelli, S; Crichton, W A; Le Bihan, T [European Synchrotron Radiation Facility, F-38043 Grenoble (France)

    2009-12-02

    The NaCl-to-Cmcm phase transition and the Cmcm structure of InAs under high pressure are studied by x-ray diffraction. The lattice parameters and fractional coordinates are given as a function of pressure. We propose a mechanism responsible for this type of symmetry breaking under pressure. We show that the ppsigma interactions do not play a major role in the stabilization of the NaCl structure. Consequently the NaCl-to-Cmcm transition occurs only in compounds with a large charge transfer. General conclusions on the behavior of III-V semiconductors under pressure are drawn.

  12. Ag-catalyzed InAs nanowires grown on transferable graphite flakes

    DEFF Research Database (Denmark)

    Meyer-Holdt, Jakob; Kanne, Thomas; Sestoft, Joachim E.;

    2016-01-01

    Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report on high aspect ratio and stacking fault free Ag-seeded InAs nanowires grown......-needle manipulator. Besides the possibilities for fabricating novel nanostructure device designs, we show how this method is used to study the parasitic growth and bicrystal match between the graphite flake and the nanowires by transmission electron microscopy....

  13. Heterogeneous nucleation of catalyst-free InAs nanowires on silicon

    Science.gov (United States)

    Gomes, U. P.; Ercolani, D.; Zannier, V.; Battiato, S.; Ubyivovk, E.; Mikhailovskii, V.; Murata, Y.; Heun, S.; Beltram, F.; Sorba, L.

    2017-02-01

    We report on the heterogeneous nucleation of catalyst-free InAs nanowires on Si(111) substrates by chemical beam epitaxy. We show that nanowire nucleation is enhanced by sputtering the silicon substrate with energetic particles. We argue that particle bombardment introduces lattice defects on the silicon surface that serve as preferential nucleation sites. The formation of these nucleation sites can be controlled by the sputtering parameters, allowing the control of nanowire density in a wide range. Nanowire nucleation is accompanied by unwanted parasitic islands, but careful choice of annealing and growth temperature allows us to strongly reduce the relative density of these islands and to realize samples with high nanowire yield.

  14. Growth and characterization of InAs quantum dots with low-density and long emission wavelength

    Institute of Scientific and Technical Information of China (English)

    Lin Li; Guojun Liu; Zhanguo Li; Mei Li; Xiaohua Wang

    2008-01-01

    The growth parameters affecting the deposition of self-assembled InAs quantum dots (QDs) on GaAs substrate by low-pressure metal-organic chemical vapor deposition (MOCVD) are reported. The low-density InAs QDs (~ 5 × 108 cm-2) are achieved using high growth temperature and low InAs coverage. Photolu-minescence (PL) measurements show the good optical quality of low-density QDs. At room temperature,the ground state peak wavelength of PL spectrum and full-width at half-maximum (FWHM) are 1361 nm and 23 meV (35 nm), respectively, which are obtained as the GaAs capping layer grown using triethylgallium (TEG) and tertiallybutylarsine (TBA). The PL spectra exhibit three emission peaks at 1361, 1280,and 1204 nm, which correspond to the ground state, the first excited state, and the second excited state of the QDs, respectively.

  15. Energetics of island formation of AlAs, GaAs, and InAs on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Geunjung; Efimov, Oleg; Yoon, Younggui [Chung-Ang University, Seoul (Korea, Republic of)

    2012-03-15

    We study the energetics of island formation of AlAs, GaAs, and InAs on Si(100)2x1 substrates from first-principles. Si(100)2x1:As is stable under As-rich conditions in all cases. Si(100)2x1:(AlAs) and Si(100)2x1:(GaAs) are stable under Al-rich and Ga-rich conditions, respectively. However, the surface energy of Si(100)2x1:InAs is higher than that of Si(100)2x1:As under In-rich conditions. The energies of thicker epitaxial overlayer films of AlAs, GaAs, and InAs are predicted to be higher than the corresponding energies of these monolayer films.

  16. Explanation of Unusual Photoluminescence Behavior from InAs Quantum Dots with InAlAs Capping

    Institute of Scientific and Technical Information of China (English)

    Zhongyuan YU; Yongqiang WEI

    2005-01-01

    The effect of different kinds of cap layers on optical property of InAs quantum dots (QDs) on GaAs (100) substrate was studied. Temperature dependent photoluminescence (PL) indicates that the PL integrated intensity from the ground state of InAs QDs capped with an intermediate InAlAs layer drops very little as compared to QDs capped with a thin InGaAs or GaAs cap layer from 15 K up to room temperature. PL integrated intensity ratio of the first excited to ground states for InAs QDs capped with an intermediate InAlAs layer is unexpectedly decreased with increasing temperature, which are attributed to phonon bottleneck effect. A virtual barrier is proposed to describe this physics process and shows good agreement with experimental results when fitting the curve with the value of the virtual barrier 30 meV.

  17. Droplet epitaxy growth of telecom InAs quantum dots on metamorphic InAlAs/GaAs(111)A

    Science.gov (United States)

    Ha, Neul; Mano, Takaaki; Kuroda, Takashi; Mitsuishi, Kazutaka; Ohtake, Akihiro; Castellano, Andrea; Sanguinetti, Stefano; Noda, Takeshi; Sakuma, Yoshiki; Sakoda, Kazuaki

    2015-04-01

    We demonstrated the droplet epitaxial growth of InAs quantum dots on a GaAs(111)A substrate, which emitted at telecommunication wavelengths. A high-quality metamorphic In0.52Al0.48As layer was formed by inserting three monolayers of InAs between GaAs(111)A and InAlAs. InAs quantum dots were grown on the InAlAs surface by droplet epitaxy. They exhibited a laterally symmetrical shape owing to the C3v symmetry of the {111} surface. The photoluminescence signals of capped quantum dots indicated broadband spectra covering wavelengths from 1.3 to 1.55 µm. Thus, our dots are potentially useful for constructing entangled photon sources compatible with current telecommunication networks.

  18. Temperature-Dependent Galvanomagnetic Measurements on Doped InSb and InAs Grown by Liquid Encapsulated Czochralski

    Institute of Scientific and Technical Information of China (English)

    M. Kasap; S. Acar; S. (O)z(c)elik; S. Karadeniz2; N. Tu(g)luo(g)lu

    2005-01-01

    @@ Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped InSb and S-doped InAs samples grown by the liquid encapsulated Czochralski technique were carried out as a function of temperature (14-350 K) and magnetic field (0-1.35 T). In Te-doped InSb, an impurity level with energy E1 -= 3 meV and the activation energy Eo =- 0.26 eV, which is the band gap energy, are obtained from the resistivity and Hall carrier concentration analysis. In S-doped InAs, both the linear and power law models are used in explaining the temperature-dependent resistivity. The effects of impurities on the electron and magnetic transportation properties of InAs and InSb have also been discussed.

  19. Passivation of InAs and GaSb with High κ Dielectrics - Growth, Structural, Chemical and Electrical Characterization

    Science.gov (United States)

    2011-04-21

    chemical and electronic characteristics on Al2O3/ Gd2O3 /InAs interface were studied using x-ray photoelectron spectroscopy ( XPS ). Electrical...Al2O3. Energy-band offsets of the ALD-Al2O3/ Gd2O3 /InAs were obtained using XPS . The valence-band offset ~3.92 eV was determined by measuring the...94, 052106 (2009)   Fig. 1 (a valence b CLs at A and Al 2 film. (b) E ) XPS spe and of InA LD-Al2O p CL and nergy-ban ctra of As s film, Al 2 3/ Gd2O3

  20. Fe-contacts on InAs(100) and InP(100) characterised by conversion electron Mössbauer spectroscopy

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Gunnlaugsson, H.P; Weyer, G.;

    2005-01-01

    We have grown 4 nm thin films of Fe-57 on InAs(100) and InP(100) surfaces by use of MBE and studied the samples by Fe-57 conversion electron Mossbauer spectroscopy. In the case of InAs, the Mossbauer spectrum showed a sextet due to alpha-Fe and a further magnetically split component with slightly...

  1. Growth of InAs Quantum Dots on GaAs (511)A Substrates: The Competition between Thermal Dynamics and Kinetics.

    Science.gov (United States)

    Wen, Lei; Gao, Fangliang; Zhang, Shuguang; Li, Guoqiang

    2016-08-01

    The growth process of InAs quantum dots grown on GaAs (511)A substrates has been studied by atomic force microscopy. According to the atomic force microscopy studies for quantum dots grown with varying InAs coverage, a noncoherent nucleation of quantum dots is observed. Moreover, due to the long migration length of In atoms, the Ostwald ripening process is aggravated, resulting in the bad uniformity of InAs quantum dots on GaAs (511)A. In order to improve the uniformity of nucleation, the growth rate is increased. By studying the effects of increased growth rates on the growth of InAs quantum dots, it is found that the uniformity of InAs quantum dots is greatly improved as the growth rates increase to 0.14 ML s(-1) . However, as the growth rates increase further, the uniformity of InAs quantum dots becomes dual-mode, which can be attributed to the competition between Ostwald ripening and strain relaxation processes. The results in this work provide insights regarding the competition between thermal dynamical barriers and the growth kinetics in the growth of InAs quantum dots, and give guidance to improve the size uniformity of InAs quantum dots on (N11)A substrates.

  2. Growth of InGaAs-capped InAs quantum dots characterized by Atomic Force Microscope and Scanning Electron Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shende; Tsai Chiouyun; Lee Sichen [National Taiwan University, Department of Electrical Engineering, Graduate Institute of Electronics Engineering (China)

    2004-08-15

    Atomic force microscopy (AFM) is typically used to measure the quantum dot shape and density formed by lattice mismatched epitaxial growth such as InAs on GaAs. However, AFM images are distorted when two dots are situated in juxtaposition with a distance less than the AFM tip width. Scanning electron Microscope (SEM) is much better in distinguishing the dot density but not the dot height. Through these measurements of the growth of In{sub x}Ga{sub 1-x}As cap layer on InAs quantum dots, it was observed that the InGaAs layer neither covered the InAs quantum dots and wetting layer uniformly nor 100% phase separates into InAs and GaAs grown on InAs quantum dots and wetting layer, respectively.

  3. Preparation and properties of InAs 50 mol%-CuInSesub(2) 50 mol% alloy

    Energy Technology Data Exchange (ETDEWEB)

    Al-Douri, A.A.J. [University of Baghdad (Iraq). College of Science; Hasoon, F.S.; Kazmerski, L.L. [National Renewable Energy Laboratory, Golden, CO (United States)

    1998-01-01

    Continuing our search on semiconducting compounds and alloys, the InAs 50 mol%-CuInSesub(2) 50 mol% alloy was investigated. Both InAs and CuInSe are adamantine which satisfies the four electron per atom rule. A large single crystal ingot was carefully prepared using the vertical Bridgmans method. The specimen was examined by room temperature and temperature dependence X-ray powder photography, Electron Probe Microanalysis (EPMA), Differential Thermal Analysis (DTA), and Vickers hardness test. (author)

  4. Raman Spectroscopy of InAs Based Nanowires & Electronic Characterization of Heterostructure InAs/GaInAs Nanowires

    DEFF Research Database (Denmark)

    Tanta, Rawa

    spectroscopy measurements on InAs based nanowires include several topics. Firstly, we use polarized Raman spectroscopy for determining the crystal orientation of the nanowires based on conventional Raman selection rules. We studied the effect of the high power laser irradiation on the nanowire, and its......The work presented in this thesis represents two main topics. The first one, which covers a bigger volume of the thesis, is mainly about Raman spectroscopy on individual InAs based nanowires. The second part presents electronic characterization of heterostructure InAs/GaInAs nanowires. Raman...

  5. Full thermoelectric characterization of InAs nanowires using MEMS heater/sensors.

    Science.gov (United States)

    Karg, S F; Troncale, V; Drechsler, U; Mensch, P; Das Kanungo, P; Schmid, H; Schmidt, V; Gignac, L; Riel, H; Gotsmann, B

    2014-08-01

    Precise measurements of a complete set of thermoelectric parameters on a single indium-arsenide nanowire (NW) have been performed using highly sensitive, micro-fabricated sensing devices based on the heater/sensor principle. The devices were fabricated as micro electro-mechanical systems consisting of silicon nitride membranes structured with resistive gold heaters/sensors. Preparation, operation and characterization of the devices are described in detail. Thermal decoupling of the heater/sensor platforms has been optimized reaching thermal conductances as low as 20 nW K(-1) with a measurements sensitivity below 20 nW K(-1). The InAs NWs were characterized in terms of thermal conductance, four-probe electrical conductance and thermopower (Seebeck coefficient), all measured on a single NW. The temperature dependence of the parameters determining the thermoelectric figure-of-merit of an InAs NW was acquired in the range 200-350 K featuring a minor decrease of the thermal conductivity from 2.7 W (m K)(-1) to 2.3 W (m K)(-1).

  6. X-ray characterization Si-doped InAs nanowires grown on GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Saqib, Muhammad; Biermanns, Andreas; Pietsch, Ullrich [Universitaet Siegen, Festkoerperphysik (Germany); Grap, Thomas; Lepsa, Mihail [Forschungszentrum Juelich, Institut fuer Bio- und Nanosysteme (Germany)

    2011-07-01

    Semiconductor nanowires (NW) are of particular interest due to the ability to synthesize single-crystalline 1D epitaxial structures and heterostructures in the nanometer range. However, many details of the growth mechanism are not well understood. In particular, understanding and control of doping mechanisms during NW growth are important issues for technological applications. In this contribution we present a x-ray diffraction study of the influence of Si-doping in InAs NWs grown on GaAs(111) substrates using In-assisted MBE growth. With the help of coplanar and asymmetric x-ray diffraction, we monitor the evolution of the lattice constants and structure of the InAs NWs as function of doping concentration. We observe that increasing the nominal doping concentration leads to the appearance of additional diffraction maxima corresponding to material whose vertical lattice parameter is 1% smaller than that of the undoped nanowires. Those lattice parameters can be attributed with alloy formation in the form of island like crystallites.

  7. Ultrafast dynamics of surface plasmons in InAs by time-resolved infrared nanospectroscopy.

    Science.gov (United States)

    Wagner, Martin; McLeod, Alexander S; Maddox, Scott J; Fei, Zhe; Liu, Mengkun; Averitt, Richard D; Fogler, Michael M; Bank, Seth R; Keilmann, Fritz; Basov, D N

    2014-08-13

    We report on time-resolved mid-infrared (mid-IR) near-field spectroscopy of the narrow bandgap semiconductor InAs. The dominant effect we observed pertains to the dynamics of photoexcited carriers and associated surface plasmons. A novel combination of pump-probe techniques and near-field nanospectroscopy accesses high momentum plasmons and demonstrates efficient, subpicosecond photomodulation of the surface plasmon dispersion with subsequent tens of picoseconds decay under ambient conditions. The photoinduced change of the probe intensity due to plasmons in InAs is found to exceed that of other mid-IR or near-IR media by 1-2 orders of magnitude. Remarkably, the required control pulse fluence is as low as 60 μJ/cm(2), much smaller than fluences of ∼ 1-10 mJ/cm(2) previously utilized in ultrafast control of near-IR plasmonics. These low excitation densities are easily attained with a standard 1.56 μm fiber laser. Thus, InAs--a common semiconductor with favorable plasmonic properties such as a low effective mass--has the potential to become an important building block of optically controlled plasmonic devices operating at infrared frequencies.

  8. Controlling the transport properties of InAs nanowires by Si doping

    Energy Technology Data Exchange (ETDEWEB)

    Weis, Karl; Wirths, Stephan; Winden, Andreas; Sladek, Kamil; Schaepers, Thomas; Hardtdegen, Hilde; Lueth, Hans; Demarina, Nataliya; Gruetzmacher, Detlev [Institut fuer Bio- und Nanosysteme (IBN), Forschungszentrum Juelich (Germany); JARA, Fundamentals of Future Information Technology (Germany); Weirich, Thomas [Gemeinschaftslabor fuer Elektronenmikroskopie, RWTH Aachen (Germany); JARA, Fundamentals of Future Information Technology (Germany)

    2011-07-01

    InAs nanowires are attractive building blocks for nanoelectronic devices, e. g. field-effect transistors. For concrete applications, it is important to understand the interplay between their crystal structure and transport properties. By doping, the latter can be tuned. We fabricated InAs nanowires by selective-area metal-organic vapour phase epitaxy. Using Si{sub 2} H{sub 6} as a dopant, samples with five different doping levels, each set comprising 30 to 100 nanowires (typical length and diameter: 3 {mu} m and 100 nm, respectively), were prepared. From I-V measurements and field effect transistor measurements using a SiO{sub 2} back gate, we get a clear positive correlation between doping level and conductivity/carrier concentration/mobility. The conductivity can be tuned between (12.9{+-} 0.8) S/cm and (560 {+-} 120) S/cm. Furthermore, transmission electron micrographs show an influence of doping on the crystal structure of the wires. Magneto-transport measurements are performed to quantify the effect of stacking faults on the conductivity. At low temperatures around 4 K, the I-V characteristics show indications of single electron tunneling.

  9. InAs quantum well μ-Hall sensors for magnetic biosensing

    Science.gov (United States)

    Aledealat, Khaled; Hira, S.; Chen, K.; Mihajlovic, G.; Xiong, P.; Strouse, G.; Chase, P. B.; von Molnar, S.; Field, M.; Sullivan, G.

    2008-03-01

    Magnetic sensing is potentially a sensitive and rapid technique for monitoring DNA-DNA and protein-DNA interactions. Here we present an effort on the noise characterization and selective biofunctionalization of InAs μ-Hall sensors for magnetic detection of DNA hybridization. Room-temperature noise measurements were performed in the frequency range from 20 Hz to 104 kHz. The noise equivalent magnetic moment resolutions were estimated to be ˜10^6 μB/√Hz and ˜10^4 μB/√Hz at 92 Hz and 23 kHz respectively. The active region of the InAs μ-Hall device was covered with sputter-deposited SiO2 and Au pads were patterned on top of some of the Hall crosses. Thiolated ssDNA were assembled on the Au pads and the rest of the device platform was passivated with PEG-silane. Biotinylated and fluorescently-tagged complementary ssDNA were labeled with commercial streptavidin-coated 350 nm superparamagnetic beads, which were found to assemble selectively onto the Au pads through DNA hybridization using laser scanning confocal microscopy. This work was supported by NIH NIGMS GM079592.

  10. Label-free detection of DNA hybridization using InAs μ-Hall sensors

    Science.gov (United States)

    Aledealat, Khaled; Hira, S.; Chen, K.; Strouse, G. F.; Chase, P. B.; Xiong, P.; von Molnar, S.; Mihajlovic, G.; Field, M.; Sullivan, G.

    2010-03-01

    We present results on label-free detection of DNA hybridization using InAs μ-Hall sensors. The μ-Hall sensor consisted of six 1-μm Hall crosses defined on an InAs quantum well substrate. The sensor was then covered with sputter-deposited SiO2 and Au pads were patterned on top of some of the Hall crosses. Thiolated ssDNA strands that are complementary to one end of the target ssDNA were assembled on the Au pads and the rest of the device platform was passivated with PEG-silane. Biotinylated and fluorescently-tagged complementary ssDNA to the other end of the target ssDNA were labeled with commercial streptavidin-coated 350 nm superparamagnetic beads. Labeled ssDNA were found to assemble selectively onto the Au pads after mixing with the target ssDNA, indicating successful hybridization of the three ssDNA sequences. The presence of the assembled beads was successfully detected via the Hall sensor and confirmed using laser scanning confocal microscopy. This work was supported by NIH NIGMS GM079592.

  11. The effect of gate control on the electrical conductivity of InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Weis, Karl; Volk, Christian; Wirths, Stephan; Estevez Hernandez, Sergio; Akabori, Masashi; Sladek, Kamil; Penz, Andreas; Trellenkamp, Stefan; Schubert, Juergen; Schaepers, Thomas; Hardtdegen, Hilde; Gruetzmacher, Detlev [Institut fuer Bio- und Nanosysteme (IBN-1), Forschungszentrum Juelich (Germany); JARA, Fundamentals of Future Information Technology (Germany)

    2010-07-01

    Semiconductor nanowires are an interesting step on the road to zero-dimensional systems. InAs is an especially suitable material because ohmic contacts can be prepared straightforwardly. Provided sufficient gate control, quantum dots can be formed. Here, the electronic transport properties of nominally undoped InAs nanowires grown by metal-organic vapour phase epitaxy are examined. Their typical length and diameter are 5 {mu}m and 100 nm, respectively. The gate control is studied for different gate geometries, e. g. fingers, back- and top-gates. Furthermore, we compare the performance of high-k dielectrics, e. g. GdScO{sub 3} or LaLuO{sub 3}, with standard dielectrics like SiO{sub 2} or Si{sub 3}N{sub 4}. Four-terminal transport measurements are performed both at room temperature as well as at low temperatures down to 30 mK. Field effect transistor measurements performed at room temperature show that by using high-k dielectrics, the I{sub on}/I{sub off} ratio can be improved by at least one order of magnitude.

  12. InAs 2DEGs:What's the g-factor?

    Science.gov (United States)

    McCombe, B. D.; Pakmehr, Mehdi; Khaetskii, A.; Chiatti, Olivio; Fischer, S. F.; Buchholz, S.; Heyn, C.; Hansen, W.; Cahay, M.; Newrock, R. S.; Bandari, Nikhil

    2014-03-01

    Interest in spin-orbit effects in semiconductors has led us to study the electron g-factor in quasi-2DEG InAs samples. We have made magneto-transport and -photoresponse (PR) measurements on InAs QW structures in magnetic fields up to 10 T. THz cyclotron resonance (CR) is manifested in PR as a resonant envelope of the amplitude of quantum oscillations, which show clear spin-splitting (for lower mobility samples) down 4T, while direct R_xx measurements show no spin-splitting up to 9T. R_xx oscillations in a higher mobility sample show well-resolved spin-splittings over a range of fields as does the PR. We have simulated the data with a theoretical expression for 2DEG SdH oscillations (coupled with CR resonant carrier heating for the PR) and extracted g-factors from fits. We also used a different (commonly used) method, SdH oscillations vs. tilt angle of the field to extract g-factors from the angle at which the SdH frequency doubles. We find very large g-factors from fits to R_xx and PR (14 - 20), but g-factors 2-3 times smaller for these same samples from tilted field experiments (close to estimated band g-factors). These results are discussed in terms of exchange effects. Support: NSF DMR 1008138 (Buffalo); NSF ECCE 1028483(Cincinnati); DFG Fi932/4-1(Berlin).

  13. A Stably Transgenic INA Enterobacter cloacae for Control of Insect Pests

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-jian; SUN Fu-zai; ZHAO Ting-chang; DING Ai-yun; TANG Chao-rong

    2003-01-01

    Using the minitransposon pMini-Tn5 and the ice-nucleation active (INA) gene of iceA, a suicide recombinant plasmid pTnice1 was constructed, which has the ability of broad-host-range conjugal mobilization and integration of iceA into chromosomal DNA of many gram-negative bacteria by Tn5 transposition.We used this plasmid to integrate the iceA into chromosomal DNA of Ent. cloacae and obtained the transgentic strain Enc1. 2022ina. In this transgenic Ent. cloacae, iceA would never be transferred elsewhere through transposition, and constantly expressed high ice nucleation activity even in the absence of antibiotic pressure.The transgenic strain was ingested by corn borer larvae. Over the 7 d after ingestion, the mean supercooling points (SCPs) of the larvae was about 10℃ higher than those of larvae treated with distilled water (control).The maintenance of these high SCPs was related to the stable gut colonization of transgenic strain. At 6th day post ingestion, the larva was exposed at - 5 or - 7℃ for 12 h, the percentages of larvae frozen to death were 85and 100%, respectively. In contrast, none or a small proportion of control larvae was frozen to death under the same conditions. Further studies demonstrated that this transgenic strain bore weak epiphytic ability.Therefore, this genetically engineered strain may be a promising candidate for control of insect pests in agricultural fields.

  14. Implementing nuclear non-proliferation in Finland. Regulatory control, international cooperation and the Comprehensive Nuclear-Test-Ban Treaty. Annual report 2011

    Energy Technology Data Exchange (ETDEWEB)

    Okko, O. (ed.)

    2012-07-01

    The regulatory control of nuclear materials (i.e. nuclear safeguards) is a prerequisite for the peaceful use of nuclear energy in Finland. Safeguards are required for Finland to comply with international agreements on nuclear non-proliferation - mainly the Non-Proliferation Treaty (NPT). This regulatory control is exercised by the Nuclear Materials Section of the Finnish Radiation and Nuclear Safety Authority (STUK). The results of STUK's nuclear safeguards inspection activities in 2011 continued to demonstrate that the Finnish licence holders take good care of their nuclear materials. There were no indications of undeclared nuclear materials or activities and the inspected materials and activities were in accordance with the licence holders' declarations.

  15. ESR and AMS-based 14C Dating of Mousterian Levels at Mujina Pećina, Dalmatia, Croatia

    NARCIS (Netherlands)

    Rink, W.J.; Karavanić, I.; Pettitt, P.B.; Plicht, J. van der; Smith, F.H.; Bartoll, J.; Karavanic, I.

    2002-01-01

    This paper presents the first chronometric dates for sediments that contain a Mousterian industry in Dalmatia (south Croatia). Electron spin resonance (ESR) dating was conducted on two teeth from the Mousterian level E1 at the site of Mujina Pećina. Additionally five bone and one charcoal sample fro

  16. 20 CFR 668.360 - What is the role of INA grantees in the One-Stop system?

    Science.gov (United States)

    2010-04-01

    ... Services to Customers § 668.360 What is the role of INA grantees in the One-Stop system? (a) In those local... participate in the One-Stop system in that area in order to receive WIA services. (b) At a minimum, the MOU... program; (4) As necessary to provide referrals and case management services, the exchange of information...

  17. Critical surface phase of α2(2 × 4) reconstructed zig-zag chains on InAs(001)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiang [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); Zhou, Xun [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); School of Physics and Electronics Science, Guizhou Normal University, Guizhou, Guiyang 550001 (China); Wang, Ji-Hong [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); Luo, Zi-Jiang [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); School of Education Administration, Guizhou University of Finance and Economics, Guizhou, Guiyang 550004 (China); Zhou, Qing; Liu, Ke; Hu, Ming-Zhe [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China); Ding, Zhao, E-mail: zding@gzu.edu.cn [Department of Electronic Information Science and Technology, Guizhou University, Guizhou, Guiyang 550025 (China)

    2014-07-01

    The critical condition for InAs(001) surface phase transition has been studied, the surface phase transition of InAs(001) showed discontinuity with hysteresis cycle as a function of substrate temperature. A mixed reconstruction surface and zig-zag chain α2(2 × 4) reconstruction surface have been observed by scanning tunneling microscopy. Considering the interaction and dynamics of surface arsenic atoms, the zig-zag chains of α2(2 × 4) reconstruction were found to be actually caused by the selective adsorption and desorption of surface arsenic dimers, they played a critical role in the surface phase transition between (2 × 4) and (4 × 2). - Highlights: • Discontinuous surface phase transition phenomena on the flat InAs(001) surface • Nanoscale InAs(001) surface observed by scanning tunneling microscopy • “Zig-Zag” chains of α2(2 × 4) reconstruction • Critical role in the surface phase transition between (2 × 4) and (4 × 2)

  18. 20 CFR 668.240 - What is the process for applying for designation as an INA grantee?

    Science.gov (United States)

    2010-04-01

    ... which the entity requests designation; (5) A brief summary of the employment and training or human resource development programs serving Native Americans that the entity currently operates or has operated... designation as an INA grantee? 668.240 Section 668.240 Employees' Benefits EMPLOYMENT AND TRAINING...

  19. New process for high optical quality InAs quantum dots grown on patterned GaAs(001) substrates

    NARCIS (Netherlands)

    Alonso-González, Pablo; González, Luisa; González, Yolanda; Fuster, David; Fernández-Martinez, Ivan; Martin-Sánchez, Javier; Abelmann, Leon

    2007-01-01

    This work presents a selective ultraviolet (UV)-ozone oxidation-chemical etching process that has been used, in combination with laser interference lithography (LIL), for the preparation of GaAs patterned substrates. Further molecular beam epitaxy (MBE) growth of InAs results in ordered InAs/GaAs qu

  20. EXAMINING THE ROLE AND RESEARCH CHALLENGES OF SOCIAL MEDIA AS A TOOL FOR NONPROLIFERATION AND ARMS CONTROL TREATY VERIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Michael J.; Cramer, Nicholas O.; Benz, Jacob M.; Gastelum, Zoe N.; Kreyling, Sean J.; West, Curtis L.

    2014-05-13

    Traditional arms control treaty verification activities typically involve a combination of technical measurements via physical and chemical sensors, state declarations, political agreements, and on-site inspections involving international subject matter experts. However, the ubiquity of the internet, and the electronic sharing of data that it enables, has made available a wealth of open source information with the potential to benefit verification efforts. Open source information is already being used by organizations such as the International Atomic Energy Agency to support the verification of state-declared information, prepare inspectors for in-field activities, and to maintain situational awareness . The recent explosion in social media use has opened new doors to exploring the attitudes, moods, and activities around a given topic. Social media platforms, such as Twitter, Facebook, and YouTube, offer an opportunity for individuals, as well as institutions, to participate in a global conversation at minimal cost. Social media data can also provide a more data-rich environment, with text data being augmented with images, videos, and location data. The research described in this paper investigates the utility of applying social media signatures as potential arms control and nonproliferation treaty verification tools and technologies, as determined through a series of case studies. The treaty relevant events that these case studies touch upon include detection of undeclared facilities or activities, determination of unknown events recorded by the International Monitoring System (IMS), and the global media response to the occurrence of an Indian missile launch. The case studies examine how social media can be used to fill an information gap and provide additional confidence to a verification activity. The case studies represent, either directly or through a proxy, instances where social media information may be available that could potentially augment the evaluation

  1. Privacy Act

    Science.gov (United States)

    Learn about the Privacy Act of 1974, the Electronic Government Act of 2002, the Federal Information Security Management Act, and other information about the Environmental Protection Agency maintains its records.

  2. Characterization and Effect of Thermal Annealing on InAs Quantum Dots Grown by Droplet Epitaxy on GaAs(111)A Substrates.

    Science.gov (United States)

    Bietti, Sergio; Esposito, Luca; Fedorov, Alexey; Ballabio, Andrea; Martinelli, Andrea; Sanguinetti, Stefano

    2015-12-01

    We report the study on formation and thermal annealing of InAs quantum dots grown by droplet epitaxy on GaAs (111)A surface. By following the changes in RHEED pattern, we found that InAs quantum dots arsenized at low temperature are lattice matched with GaAs substrate, becoming almost fully relaxed when substrate temperature is increased. Morphological characterizations performed by atomic force microscopy show that annealing process is able to change density and aspect ratio of InAs quantum dots and also to narrow size distribution.

  3. Report of a workshop on nuclear power growth and nonproliferation held at the Woodrow Wilson international center for scholars, Washington, DC, April 21, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Pilat, Joseph F [Los Alamos National Laboratory

    2010-01-01

    The workshop addressed the future of nuclear power and nonproliferation in light of global nuclear energy developments, changing US policy and growing concerns about nuclear proliferation and terrorism. The discussion reflected wide agreement on the need for nuclear power, the necessity of mitigating any proliferation and terrorism risks and support for international cooperation on solutions. There were considerable differences on the nature and extent of the risks of differing fuel cycle choices. There was some skepticism about the prospects for a global nuclear energy renaissance, but there was a recognition that nuclear power would expand somewhat in the decades ahead with some states expanding capacity dramatically (e.g., China) and at least a few new states developing nuclear power programs. It was also argued by some participants that under the right conditions, a genuine renaissance could occur some decades from now. The prospects for a dramatic growth in nuclear power will depend on the ability of governments and industry to address these concerns, including the effectiveness of, and the resources devoted to, plans to develop and implement technologies and approaches that strengthen nonproliferation, nuclear materials accountability and nuclear security Several participants noted that the United States will not be able to continue to lead global nonproliferation efforts and to shape the growth of nuclear power as well as the global environment and energy debates without a robust US nuclear energy program. Some participants argued that fully integrating nuclear energy growth and nonproliferation, proliferation resistance and physical protection objectives was possible. The growing consensus on these objectives and the growing concern about the potential impact of further proliferation on the industry was one reason for optimism. The Blue Ribbon commission led by Scowcroft and Hamilton was seen as going far beyond the need to find an alternative to Yucca

  4. Cooperation in Nuclear Waste Management, Radiation Protection, Emergency Preparedness, Reactor Safety and Nuclear Non-Proliferation in Eastern Europe

    Energy Technology Data Exchange (ETDEWEB)

    Dassen, Lars van; Delalic, Zlatan; Ekblad, Christer; Keyser, Peter; Turner, Roland; Rosengaard, Ulf; German, Olga; Grapengiesser, Sten; Andersson, Sarmite; Sandberg, Viviana; Olsson, Kjell; Stenberg, Tor

    2009-10-15

    The Swedish Radiation Safety Authority (SSM) is trusted with the task of implementing Sweden's bilateral assistance to Russia, Ukraine, Georgia, Belarus and Armenia in the fields of reactor safety, nuclear waste management, nuclear non-proliferation as well as radiation protection and emergency preparedness. In these fields, SSM also participates in various projects financed by the European Union. The purpose of this project-oriented report is to provide the Swedish Government and other funding agencies as well as other interested audiences in Sweden and abroad with an encompassing understanding of our work and in particular the work performed during 2008. the activities are divided into four subfields: Nuclear waste management; Reactor safety; Radiation safety and emergency preparedness; and, Nuclear non-proliferation. SSM implements projects in the field of spent nuclear fuel and radioactive waste management in Russia. The problems in this field also exist in other countries, yet the concentration of nuclear and radioactive materials are nowhere higher than in north-west Russia. And given the fact that most of these materials stem from the Cold War era and remain stored under conditions that vary from 'possibly acceptable' to 'wildly appalling' it is obvious that Sweden's first priority in the field of managing nuclear spent fuel and radioactive waste lies in this part of Russia. The prioritisation and selection of projects in reactor safety are established following thorough discussions with the partners in Russia and Ukraine. For specific guidance on safety and recommended safety improvements at RBMK and VVER reactors, SSM relies on analyses and handbooks established by the IAEA in the 1990s. In 2008, there were 16 projects in reactor safety. SSM implements a large number of projects in the field of radiation protection and emergency preparedness. The activities are at a first glance at some distance from the activities covered and

  5. Biosafety and biosecurity as essential pillars of international health security and cross-cutting elements of biological nonproliferation

    Directory of Open Access Journals (Sweden)

    Perkins Dana

    2010-12-01

    Full Text Available Abstract The critical aspects of biosafety, biosecurity, and biocontainment have been in the spotlight in recent years. There have also been increased international efforts to improve awareness of modern practices and concerns with regard to the safe pursuit of life sciences research, and to optimize current oversight frameworks, thereby resulting in decreased risk of terrorist/malevolent acquisition of deadly pathogens or accidental release of a biological agent, and increased safety of laboratory workers. Our purpose is to highlight how the World Health Organization’s (WHO revised International Health Regulations (IHR[2005], the Biological Weapons Convention (BWC, and the United Nations Security Council Resolution (UNSCR 1540 overlap in their requirements with regard to biosafety and biosecurity in order to improve the understanding of practitioners and policymakers and maximize the use of national resources employed to comply with internationally-mandated requirements. The broad range of goals of these international instruments, which are linked by the common thread of biosafety and biosecurity, highlight their significance as essential pillars of international health security and cross-cutting elements of biological nonproliferation. The current efforts of the Republic of Georgia to enhance biosafety and biosecurity in accordance with these international instruments are summarized.

  6. Arms Control and nonproliferation technologies: Technology options and associated measures for monitoring a Comprehensive Test Ban, Second quarter

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Leslie A.

    1994-01-01

    This newsletter contains reprinted papers discussing technology options and associated measures for monitoring a Comprehensive Test Ban Treaty (CTBT). These papers were presented to the Conference on Disarmament (CD) in May and June 1994. An interagency Verification Monitoring Task Force developed the papers. The task force included participants from the Arms Control and Disarmament Agency, the Department of Defense, the Department of Energy, the Intelligence Community, the Department of Interior, and the Department of State. The purpose of this edition of Arms Control and Nonproliferation Technologies is to share these papers with the broad base of stakeholders in a CTBT and to facilitate future technology discussions. The papers in the first group discuss possible technology options for monitoring a CTBT in all environments (underground, underwater, atmosphere, and space). These technologies, along with on-site inspections, would facilitate CTBT monitoring by treaty participants. The papers in the second group present possible associated measures, e.g., information exchanges and transparency measures, that would build confidence among states participating in a CTBT.

  7. Mieloencefalite protozoária eqüina (Relato de caso.

    Directory of Open Access Journals (Sweden)

    R. C. Gonçalves

    2005-03-01

    Full Text Available RESUMO :O objetivo deste trabalho foi relatar um caso de mieloencefalite protozoária eqüina no Estado de São Paulo, Brasil. O diagnóstico se baseou nos sinais clínicos, no resultado positivo para anticorpos contra Sarcocystis neurona no soro e no líquor pela técnica de Western blot. Palavras chave: Mieloencefalite, Sarcocystis neurona, eqüinos. SUMMARY: The purpose of this work was to present a case of equine protozoal myeloencephalitis (EPM in the State of São Paulo, Brazil. The diagnosis was based on the clinical sings, the positive results of the serum and cerebrospinal fluid analysis (Western blot for antibodies against Sarcocystis neurona. Keywords: Myeloencephalitis, Sarcocystis neurona,

  8. Perpendicular spin injection and polarization features in InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D. [Lehrstuhl fuer Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum (Germany); Soldat, Henning; Li, Mingyuan; Gerhardt, Nils C.; Hofmann, Martin [Lehrstuhl fuer Photonik und Terahertztechnologie, Ruhr-Universitaet Bochum (Germany); Stromberg, Frank; Warland, Anne; Wende, Heiko; Keune, Werner [Fachbereich Physik, Center for Nanointegration Duisburg-Essen, Universitaet Duisburg-Essen (Germany); Ebbing, Astrid [Lehrstuhl fuer Angewandte Festkoerperphysik, Ruhr-Universitaet Bochum (Germany); Experimentalphysik IV - Festkoerperphysik, Ruhr-Universitaet Bochum (Germany); Petracic, Oleg [Experimentalphysik IV - Festkoerperphysik, Ruhr-Universitaet Bochum (Germany)

    2011-07-01

    Self assembled InAs quantum dots (QDs) are zero dimensional multilevel systems with long spin relaxation times and thus offer great potential for spin optoelectronic research and applications. Electrically injected spin polarization is efficiently transferred into circularly polarized photons if the injected spin is oriented perpendicularly to the growth plane. The optical polarization from an ensemble of QDs in a spin-LED is strongly magnetic field dependent due to the orbital character of the transitions of excited carriers. An unambiguous separation of spin injection and Zeeman shift is obtained by investigating the magnetic field dependence of the circular polarisation of the spin-LED emission. Here we present and analyze perpendicular spin injection from Fe/Tb magnetic injectors at room temperature and in remanence. Polarization features of excited transitions are discussed.

  9. Limits to mobility in InAs quantum wells with nearly lattice-matched barriers

    Science.gov (United States)

    Shojaei, B.; Drachmann, A. C. C.; Pendharkar, M.; Pennachio, D. J.; Echlin, M. P.; Callahan, P. G.; Kraemer, S.; Pollock, T. M.; Marcus, C. M.; Palmstrøm, C. J.

    2016-12-01

    The growth and density dependence of the low temperature mobility of a series of two-dimensional electron systems confined to unintentionally doped, low extended defect density InAs quantum wells with A l1 -xG axSb barriers are reported. The electron-mobility-limiting scattering mechanisms were determined by utilizing dual-gated devices to study the dependence of mobility on carrier density and electric field independently. Analysis of possible scattering mechanisms indicate the mobility was limited primarily by rough interfaces in narrow quantum wells and a combination of alloy disorder and interface roughness in wide wells at high carrier density within the first occupied electronic subband. At low carrier density, the functional dependence of mobility on carrier density provided evidence of Coulombic scattering from charged defects. A gate-tuned electron mobility exceeding 750 000 c m2V-1s-1 was achieved at a sample temperature of 2 K.

  10. Mid-infrared surface plasmon coupled emitters utilizing intersublevel transitions in InAs quantum dots.

    Energy Technology Data Exchange (ETDEWEB)

    Lyon, Stephen A. (Princeton University, Princeton, NJ); Chow, Weng Wah; Passmore, Brandon Scott; Ribaudo, Troy (University of Massachusetts Lowell, Lowell, MA); Adams, David (University of Massachusetts Lowell, Lowell, MA); Wasserman, Daniel (University of Massachusetts Lowell, Lowell, MA); Shaner, Eric Arthur

    2010-08-01

    We demonstrate mid-infrared electroluminescence from intersublevel transitions in self-assembled InAs quantum dots coupled to surface plasmon modes on metal hole arrays. Subwavelength metal hole arrays with different periodicity are patterned into the top contact of the broadband (9-15 {micro}m) quantum dot material and the measured electroluminescence is compared to devices without a metal hole array. The resulting normally directed emission is narrowed and a splitting in the spectral structure is observed. By applying a coupled quantum electrodynamic model and using reasonable values for quantum dot distributions and plasmon linewidths we are able to reproduce the experimentally measured spectral characteristics of device emission when using strong coupling parameters.

  11. Towards quantitative three-dimensional characterisation of InAs quantum dots

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; Semenova, Elizaveta; Kuznetsova, Nadezda

    2011-01-01

    InAs quantum dots (QDs) grown on InP or InGaAsP are used for optical communication applications operating in the 1.3 – 1.55 μm wavelength range. It is generally understood that the optical properties of such QDs are highly dependent on their three-dimensional structural and chemical profiles....... Whilst conventional transmission electron microscopy (TEM) techniques can be used to study capped QDs in plan-view or cross-sectional geometries, the resulting images can provide ambiguous information about their three-dimensional properties. Here, we describe an approach for investigating...... the applicability of both high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) tomography and atom probe tomography (APT) to the study of surface and buried InAs/InGaAsP QDs grown by metal organic vapour phase epitaxy (MOVPE). Electron tomography was carried out in an FEI Titan TEM...

  12. Type II band alignment in InAs zinc-blende/wurtzite heterostructured nanowires.

    Science.gov (United States)

    Panda, Jaya Kumar; Chakraborty, Arup; Ercolani, Daniele; Gemmi, Mauro; Sorba, Lucia; Roy, Anushree

    2016-10-14

    In this article we demonstrate type-II band alignment at the wurtzite/zinc-blende hetero-interface in InAs polytype nanowires using resonance Raman measurements. Nanowires were grown with an optimum ratio of the above mentioned phases, so that in the electronic band alignment of such NWs the effect of the difference in the crystal structure dominates over other perturbing effects (e.g. interfacial strain, confinement of charge carriers and band bending due to space charge). Experimental results are compared with the band alignment obtained from density functional theory calculations. In resonance Raman measurements, the excitation energies in the visible range probe the band alignment formed by the E 1 gap of wurtzite and zinc-blende phases. However, we expect our claim to be valid also for band alignment near the fundamental gap at the heterointerface.

  13. Scanning near-field infrared micro-spectroscopy on buried InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Fehrenbacher, Markus; Jacob, Rainer; Winnerl, Stephan; Schneider, Harald; Helm, Manfred [Institut fuer Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden-Rossendorf (Germany); Wenzel, Marc Tobias; Krysztofinski, Anja; Ribbeck, Hans-Georg von; Eng, Lukas M. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2012-07-01

    Providing an optical resolution on the nanometer length scale, scanning near-field optical microscopy (SNOM) turned out to be a capable technique to investigate the optical properties of perovskites, buried semiconductors and single quantum dots. Thereby, the line-width of the observed resonances (5 - 8 meV) is significantly smaller than the inhomogeneously broadened line-width of other spectroscopic measurements. Using a scattering-type-SNOM (s-SNOM) combined with a tunable free-electron laser (FEL) light source we investigated the electronic structure of single InAs quantum dots, capped under a 70 nm thick GaAs layer. Spectroscopic near-field scans clearly identified two inter-sublevel transitions within the quantum dots at 85 meV and 120 meV, contrasting from the surrounding medium. Moreover, spatially scanning the s-SNOM tip at fixed excitation energies allowed mapping the 3D distribution of such buried quantum dots.

  14. Type II band alignment in InAs zinc-blende/wurtzite heterostructured nanowires

    Science.gov (United States)

    Panda, Jaya Kumar; Chakraborty, Arup; Ercolani, Daniele; Gemmi, Mauro; Sorba, Lucia; Roy, Anushree

    2016-10-01

    In this article we demonstrate type-II band alignment at the wurtzite/zinc-blende hetero-interface in InAs polytype nanowires using resonance Raman measurements. Nanowires were grown with an optimum ratio of the above mentioned phases, so that in the electronic band alignment of such NWs the effect of the difference in the crystal structure dominates over other perturbing effects (e.g. interfacial strain, confinement of charge carriers and band bending due to space charge). Experimental results are compared with the band alignment obtained from density functional theory calculations. In resonance Raman measurements, the excitation energies in the visible range probe the band alignment formed by the E 1 gap of wurtzite and zinc-blende phases. However, we expect our claim to be valid also for band alignment near the fundamental gap at the heterointerface.

  15. Tunable emission from InAs quantum dots gated with graphene

    Science.gov (United States)

    Kinnischtzke, Laura; Goodfellow, Kenneth; Chakraborty, Chitraleema; Lai, Yiming; Badolato, Antonio; Vamivakas, Nick

    We demonstrate Stark shifted photo-luminescence from InAs quantum dots (QD) using an n-i-Schottky diode where graphene has been used as the Schottky barrier material. This hybrid photonic device is motivated by the need for tunable single photon sources with high flux and storage capabilities. Photonic crystal nanocavities decorated with a single QD provide a rich environment for coupling spins and photons, in addition to accessing cavity quantum electrodynamic physics. Methods currently used for electrically tuning the QD inside the cavity suffer from a loss of the cavity quality factor, or high leakage currents in the diode which impacts the spin-photon coupling of the device. Our measurements are a first step towards using a graphene flake to electrically tune the emission of a strongly coupled QD-cavity system. NSF Grant No. DMR-1309734.

  16. Noise thermometry applied to thermoelectric measurements in InAs nanowires

    Science.gov (United States)

    Tikhonov, E. S.; Shovkun, D. V.; Ercolani, D.; Rossella, F.; Rocci, M.; Sorba, L.; Roddaro, S.; Khrapai, V. S.

    2016-10-01

    We apply noise thermometry to characterize charge and thermoelectric transport in single InAs nanowires (NWs) at a bath temperature of 4.2 K. Shot noise measurements identify elastic diffusive transport in our NWs with negligible electron-phonon interaction. This enables us to set up a measurement of the diffusion thermopower. Unlike previous approaches, we make use of a primary electronic noise thermometry to calibrate a thermal bias across the NW. In particular, this enables us to apply a contact heating scheme, which is much more efficient in creating the thermal bias as compared to conventional substrate heating. The measured thermoelectric Seebeck coefficient exhibits strong mesoscopic fluctuations in dependence on the back-gate voltage that is used to tune the NW carrier density. We analyze the transport and thermoelectric data in terms of an approximate Mott's thermopower relation and evaluate a gate-voltage to the Fermi energy conversion factor.

  17. InAs nanowire growth modes on Si (111) by gas source molecular beam epitaxy

    Science.gov (United States)

    Robson, M. T.; LaPierre, R. R.

    2016-02-01

    InAs nanowires (NWs) were grown on silicon substrates by gas source molecular beam epitaxy using five different growth modes: (1) Au-assisted growth, (2) positioned (patterned) Au-assisted growth, (3) Au-free growth, (4) positioned Au-assisted growth using a patterned oxide mask, and (5) Au-free selective-area epitaxy (SAE) using a patterned oxide mask. Optimal growth conditions (temperature, V/III flux ratio) were identified for each growth mode for control of NW morphology and vertical NW yield. The highest yield (72%) was achieved with the SAE method at a growth temperature of 440 °C and a V/III flux ratio of 4. Growth mechanisms are discussed for each of the growth modes.

  18. Tunneling spectroscopy of a 2DEG in InAs: experiment and theory

    Science.gov (United States)

    Winkler, R.; Kunze, U.; Rössler, U.

    1992-02-01

    The narrow energy gap in InAs allows us to investigate the nonparabolic subband structure of an Yb-oxide-InAs (MOS) inversion layer by measuring the tunneling current I( U) between the inversion layer and the bulk valence band. The period of Landau oscillations of d 2I/d U2 is used to determine the subband dispersion E( k‖) and the energy dependent effective mass m∗( E) of the subband electrons. The experimental results are compared with self-consistent subband calculations taking into account the nonparabolicity, the magnetic field, and - what is important here — the potential difference between inversion layer and InAs-bulk. Besides an exact numerical solution, we discuss self-consistent, but nevertheless analytical, formulations of both the triangular potential approximation and the variational approach.

  19. Purification and Characterization of Catalase from Indigenous Fungi of Neurospora crassa InaCC F226

    Directory of Open Access Journals (Sweden)

    Pugoh Santoso

    2016-08-01

    Full Text Available Microbial catalase is an important industrial enzyme that catalyzes the decomposition of hydrogen peroxide into water and oxygen. This enzyme posseses great potential of application in food, textile and pharmaceutical industries. In this paper, Neurospora crassa InaCC F226 was used to produce catalase. The aim of this research was to purify the catalase producing by Neurospora crassa InaCC F226 using gel filtration column chromatography and characterization of temperature, pH, Vmax, Km and molecular weight. In this study, the Neurospora crassa was cultured on Vogel's medium for 5 days. The cells were harvested in the 50 mM buffer sodium phosphate (pH 7 containing 3% hydrogen peroxide. Supernatant containing crude enzymes of Catalase was separated from cells by centrifugation at 15 minutes on 13000 x g and 4oC. The purification result using gel filtration was specific activity 1464.9 U/mg, 10.7 fold and 21.7% yield. Characterization of the purified enzyme toward pH and temperature optimum was 7.0 (271.6 U/mL and 40oC (286.1 U/mL. The Km and Vmax found to be 8.8 mM and 5.7 s.mM-1.  The catalase activity increased by additiom of Fe+2, Ca+2 and inhibited by EDTA, Cu+2 and Mn+2. The molecular weight of  the catalase was 59.4 kDa

  20. Giant band bending induced by Ag on InAs(110) surfaces at low temperature

    Science.gov (United States)

    Aristov, V. Yu.; Le Lay, G.; Vinh, Le Thanh; Hricovini, K.; Bonnet, J. E.

    1993-01-01

    We show by synchrotron radiation photoemission spectroscopy [G. Le Lay, V. Yu Aristov, J. Kanski, P. O. Nilsson, U. O. Karlsson, K. Hricovini, and J. E. Bonnet (unpublished)] (core levels and valence band) as well as by Kelvin probe measurements, both under illumination and in the dark, at low temperature (LT) T~=20 K and room temperature (RT) T~=300 K, that upon deposition of minute amounts of silver (about 0.01-0.1 monolayer) onto in situ well-cleaved, highly doped, n- and p-type InAs(110) surfaces, one induces a giant movement of the Fermi level EF into the conduction band. We thus create a two-dimensional (2D) electron gas at the surface (strong downwards band bending): as a matter of fact, we do observe emission of electrons from filled states up to the EF placed far above the conduction-band minimum (CBM). It is also shown that the growth is laminar at LT, while it follows a Volmer-Weber mode at RT, with indications of chemical interactions between the Ag and In atoms at both temperatures. At LT the deposited atoms interact with the dangling bonds of the In atoms and saturate them for θ~=1 monolayer (ML). At low coverages and LT, the individual Ag atoms create donorlike surface states (SS) (adsorption-induced states) and EF can be pinned by these SS in the conduction band. This leads to the formation of a 2D electron channel at the InAs surface already at θ~=0.01-0.1 ML for both types of semiconductors. At higher coverages one observes the onset of metallization for both temperatures and Ag clusters can produce another type of SS, typically metal-induced gap states near the CBM. These proposals, as well as the experimental facts, are discussed in the light of the current theoretical models of Schottky-barrier formation.

  1. Per un etimo del toponimo carsico slov. Opčina (ital. Opicina

    Directory of Open Access Journals (Sweden)

    Mario Doria

    2000-12-01

    Full Text Available II nuovo etimo1 che qui propongo per il noto toponimo carsico, slov. Opčina, ital. Opicina ( e ted. -nel passato-- Obezenach, v. sotto , le cui prime attestazioni risalgono al 1308 e 13 l l (forme documentate Obchena, Obchiena2, mi è stato suggerito dalla lettura di un elenco di toponimi dalmati (croati dell'isola di Uglian ed altre dell'arcipelago zaratino, elenco nel quale ho trovato un interessante Opatschina, il quale differisce dal nostro Opčina unicamente per la presenza, dopo la labiale, di una a, vocale, questa, che nel toponimo isolano è certamente etimologica, in quanto appartiene alla base slava opât "abbate" (in subordine al noto opatija "abbazia", vecchi adattamenti dalle voci tedesche ant. abt, apt, aptei (ted. mod. Abt, Abtei, a sua volta risalenti a lat. (tardo abbās, abbātia ecc. (cfr. Bezlaj e Skok ss.vv. opat, risp. opat. Nell'ambito delle isole quarnerine e della Dalmazia insulare la forma Opatschina non è isolata e fa compagnia ad un abbastanza noto Opat, nome di una punta, colle (m.100 e insenatura dell'isola Incoronata4, ad un Opatija dell'isola di Veglia (glagolit. a. 1633, I. Jelenic IZ 6, 1966, p. 2815 e ad un Opatova, punta all'entrata dello stretto di Catena, tra l'Isola Lunga e l'Incoronata (cfr. Segelhandbuch p. 341. Ad ogni modo, per quanto avremo da esporre a proposito del toponimo (carsico! Op(pac(chiasella, ancor più specifico appare il confronto con altra espressione toponimica insulare, questa volta dell'isola di Eso, Opatiae verth (=Wrh (a. 1392, Hilje cit. p. 696, tale e quale l'Opachiç<; del 1459 (Hilje p. 72 e l'Opačak Veli odierno (Scotti p. 136.

  2. Per in etimo del toponimo carsico slov. Opčina (ital. Opicina

    Directory of Open Access Journals (Sweden)

    Mario Doria

    2015-08-01

    Full Text Available II nuovo etimo1 che qui propongo per il noto toponimo carsico, slov. Opčina, ital. Opicina ( e ted. -nel passato-- Obezenach, v. sotto , le cui prime attestazioni risalgono al 1308 e 1311 (forme documentate Obchena, Obchiena2, mi è stato suggerito dalla lettura di un elenco di toponimi dalmati (croati dell'isola di Uglian ed altre dell'arcipelago zaratino, elenco nel quale ho trovato un interessante Opatschina 3, il quale differisce dal nostro Opčina unicamente per la presenza, dopo la labiale, di una a, vocale, questa, che nel toponimo isolano è certamente etimologica, in quanto appartiene alla base slava opât "abbate" (in subordine al noto opatija "abbazia", vecchi adattamenti dalle voci tedesche ant. abt, apt, aptei (ted. mod. Abt, Abtei, a sua volta risalenti a lat. (tardo abbās, abbātia ecc. (cfr. Bezlaj e Skok ss.vv. opât, risp. òpat. Nell'ambito delle isole quamerine e della Dalmazia insulare la forma Opatschina non è isolata e fa compagnia ad un abbastanza noto Opat, nome di una punta, colle (m.100 e insenatura dell'isola Incoronata4, ad un Opatija dell'isola di Veglia (glagolit. a. 1633, I. Jelenic JZ 6, 1966, p. 2815 e ad un Opatova, punta all'entrata dello stretto di Catena, tra l'Isola Lunga e l'Incoronata (cfr. Segelhandbuch p. 341. Ad ogni modo, per quanto avremo da esporre a proposito del toponimo (carsico! Op(pac(chiasella, ancor più specifico appare il confronto con altra espressione toponimica insulare, questa volta dell'isola di Eso, Opatiae verth (=Verh (a. 1392, Hilje cit. p. 696, tale e quale 1'0pachiaç del 1459 (Hilje p. 72 e l'Opačak Veli odiemo (Scotti p. 136.

  3. The Case for the Use of Active Social Media in Nonproliferation and Nuclear Security

    Energy Technology Data Exchange (ETDEWEB)

    Schanfein, Mark J.

    2015-10-05

    A great amount of attention and consideration is being directed at possible applications of social media in many challenging areas. The use of social media has already shown its importance in the area of disaster response, where, each citizen is essentially acting as a sensor in reporting local conditions. In the aggregate, valuable information is obtained to enable a more effective response as well as provide timely information to those in the disaster area. No one needs to be trained to understand what constitutes a disaster, so a social media data stream from the public is literally always active and ready to engage. A similar but more focused approach is the use of crowdsourcing for science, where specific challenges in areas such as mathematics, astronomy, and biology are posted to social media and solved by the crowd.

  4. Molecular beam epitaxy growth of GaAs/InAs core-shell nanowires and fabrication of InAs nanotubes.

    Science.gov (United States)

    Rieger, Torsten; Luysberg, Martina; Schäpers, Thomas; Grützmacher, Detlev; Lepsa, Mihail Ion

    2012-11-14

    We present results about the growth of GaAs/InAs core-shell nanowires (NWs) using molecular beam epitaxy. The core is grown via the Ga droplet-assisted growth mechanism. For a homogeneous growth of the InAs shell, the As(4) flux and substrate temperature are critical. The shell growth starts with InAs islands along the NW core, which increase in time and merge giving finally a continuous and smooth layer. At the top of the NWs, a small part of the core is free of InAs indicating a crystal phase selective growth. This allows a precise measurement of the shell thickness and the fabrication of InAs nanotubes by selective etching. The strain relaxation in the shell occurs mainly via the formation of misfit dislocations and saturates at ~80%. Additionally, other types of defects are observed, namely stacking faults transferred from the core or formed in the shell, and threading dislocations.

  5. The role of strain-driven in migration in the growth of self-assembled InAs quantum dots on InP

    CERN Document Server

    Yoon, S H; Lee, T W; Hwang, H D; Yoon, E J; Kim, Y D

    1999-01-01

    Self-assembled InAs quantum dots (SAQDs) were grown on InP by metalorganic chemical vapor deposition. The amount of excess InAs and the aspect ratio of the SAQD increased with temperature and V/III ratio. It is explained that the As/P exchange reaction at the surface played an important role in the kinetics of SAQD formation. Insertion of a lattice-matched InGaAs buffer layer suppressed the excess InAs formation, and lowered the aspect ratio. Moreover, the dots formed on InGaAs buffer layers were faceted, whereas those on InP were hemispherical, confirming the effect of the As/P exchange reaction. The shape of InAs quantum dots on InGaAs buffer layers was a truncated pyramid with four [136] facets and base edges parallel to directions.

  6. Analýza podmínek pro výuku tělesné výchovy v kraji Vysočina

    OpenAIRE

    Panský, David

    2008-01-01

    Title of the Paper :Condition analysis for physical training teaching in Vysočina regwn Abstract This Paper ts focused on companson of conditions and possibilities of physical training teaching m Vysočina region at selected primary and secondary schools. Research data was obtained using the inquiry method at primary and secondary schools in eighteen selected towns of the region. The obtained data from twenty seven schools was mutually compared and evaluation of particular indicators was creat...

  7. Seven law concepts on nuclear non-proliferation suggested by the International Group of Legal Experts (ILG)

    Energy Technology Data Exchange (ETDEWEB)

    Steen, G. [Djursholm (Sweden); Wredberg, L. [ILG Consultant LTD, Vienna (Austria)

    2001-03-01

    The ILG has worked as an independent group under the Swedish Support Programme on Nuclear Non-Proliferation in Central and Eastern Europe and Central Asia. The ILG's mission is concluded with this report. When developing the seven Law Concepts on national nuclear legislation that are presented in this report, the ILG has applied certain basic principles, which are firmly established in modern Western legislation. A summary of these principles is made here. They are essential cornerstones in laws and regulations that apply both to the nuclear industry and to other high technology areas, characterised by advanced safety and security requirements. Of essential importance is that the Operator alone is responsible for the fulfilment of requirements stipulated in laws and authority directives. The technical complexity of the nuclear industry and the far-reaching requirements on safety and security necessitate a qualified and complete national system of legislation and regulations. As all legislation in general, the nuclear legislation should be clear, easy to understand and give little room for misunderstandings and loopholes. It should also present the legally established requirements on safety and security in a form that facilitates the application and implementation by both state authorities, facility operators and individuals. The investigations of the causes of the Three Mile Island and Chernobyl accidents brought into focus the impact on nuclear safety from human failure. As a consequence, increased emphasis has since then been put on the development of an overall high safety culture in the nuclear field. It is recognised that a good safety culture also promotes the non-proliferation systems and safeguards measures and helps to reduce the risk of illicit trafficking. In a high safety culture environment, each individual facility employee has to be motivated and encouraged to carry out the assigned duties and responsibilities in accordance with rules and

  8. ACTS 2014

    DEFF Research Database (Denmark)

    Co-curator of ACTS 2014 together with Rasmus Holmboe, Judith Schwarzbart and Sanne Kofoed. ACTS is the Museum of Contemporary Art’s international bi-annual festival. ACTS was established in 2011 and, while the primary focus is on sound and performance art, it also looks toward socially oriented art...... various possibilities and public spaces as a stage. ACTS takes place in and around the museum and diverse locations in Roskilde city. ACTS is partly curated by the museum staff and partly by guest curators. ACTS 2014 is supported by Nordea-fonden and is a part of the project The Museum goes downtown....

  9. Magnetic detection of biotin-streptavidin binding using InAs quantum well μ-Hall sensor

    Science.gov (United States)

    Aledealat, Khaled; Chen, K.; Mihajlovic, G.; Xiong, P.; Strouse, G.; Chase, P. B.; von Molnár, S.; Field, M.; Sullivan, G. J.

    2009-03-01

    Magnetic sensors are a key component in any high-sensitivity, rapid-response, and portable platform for magnetic biosensing. InAs quantum well micro-Hall sensors have shown high potential for such a role due to their low noise level and capability to detect single micron- sized or smaller superparamagnetic beads suitable for biosensing^1. Here we present successful selective biotinylation of InAs micro-Hall sensors and directed self-assembly of 350 nm streptavidin-coated superparamagnetic beads via the biotin-streptavidin interaction. Two Hall crosses with three and two beads produced detection signals with S/N ratio of 21.3 dB and 18.4 dB respectively. In addition, our progress for in situ detection of micron-sized magnetic beads using microfluidic channel will be presented. ^1G. Mihajlovic et al., APL 87, 112502 (2005) This work was supported by NIH NIGMS GM079592.

  10. Impact of growth conditions on morphology, structure and electrical properties of MOVPE grown InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Penz, A.; Ahe, M. von der; Sladek, K.; Wirths, S.; Weis, K.; Bloemers, C.; Volk, C.; Schaepers, T.; Hardtdegen, H.; Gruetzmacher, D. [Institute of Bio- and Nanosystems (IBN-1), Forschungszentrum Juelich, 52428 Juelich (Germany); JARA - Fundamentals of Future Information Technology (Germany); Dorn, F.; Weirich, T. [GFE, Gemeinschaftslabor fuer Elektronenmikroskopie (Germany); JARA - Fundamentals of Future Information Technology (Germany)

    2011-07-01

    The bottom-up assembly of semiconductor nanowires holds promise for future nanoelectronic devices. The high room temperature carrier mobility and the narrow direct bandgap make InAs an eligible material for this application. However, as recently reported, the conductivity of InAs nanowires could be influenced detrimentally by crystal defects such as twin planes and stacking faults. In this contribution, we report on different strategies to affect the nanowire crystallographic structure. Growth is performed by selective area MOVPE on partially masked substrates. The influence of growth rate, substrate orientation and Si doping on morphological, structural and electrical properties was investigated by scanning and transmission electron microscopy and two-and four-terminal measurements. It is found that especially the growth rate reduces the stacking fault density. Furthermore we observe an increase of conductivity and a decrease of nanowire aspect ratio with higher doping concentration. A correlation between doping, growth rate and electrical characteristics will be presented.

  11. Effects of an InGaAs Cap Layer on the Optical Properties of InAs Quantum Dot Molecules

    Institute of Scientific and Technical Information of China (English)

    TIAN Peng; HUANG Li-Rong; YUAN Xiu-Hua; HUANG De-Xiu

    2011-01-01

    @@ Self-assembled InAs quantum dot molecules are grown on GaAs substrates without following any special protocols by using metal-organic chemical vapor deposition.The effects of indium composition and the thickness of the InGaAs cap layer on the optical properties of InAs quantum dot molecules are investigated by photoluminescence.With increasing indium composition and thickness of the InGaAs cap layer, the ground-state wavelength of the emission spectrum redshifts and the peak intensity decreases.In addition, the structural and optical properties of quantum dots and quantum dot molecules are comparatively studied, and the results show that when quantum dots turn into quantum dot molecules, the emission wavelength red shifts.

  12. Spin Qubits in GaAs Heterostructures and Gating of InAs Nanowires for Lowtemperature Measurements

    DEFF Research Database (Denmark)

    Nissen, Peter Dahl

    "Spintronics" is used to describes electronics based on control over the spin of the electron rather than the charge; instead of having the charge as the carrier of information, the electrons spin-state should be the target for control and detection in a given device. The spin qubit, one...... of the contenders in the race to build a large-scale quantum computer, is such a component, and research aiming to build, manipulate and couple spin qubits is looking at many materials systems to nd one where the requirements for fast control and long coherence time can be combined with ecient coupling between...... distant qubits. This thesis presents electric measurement on two of the materials systems currently at the forefront of the spin qubit race, namely InAs nanowires and GaAs/AlGaAs heterostructures. For the InAs nanowires we investigate dierent gating geometries towards the goal of dening stable quantum...

  13. Effect of nanohole size on selective area growth of InAs nanowire arrays on Si substrates

    Science.gov (United States)

    Wang, Xiaoye; Yang, Wenyuan; Wang, Baojun; Ji, Xianghai; Xu, Shengyong; Wang, Wei; Chen, Qing; Yang, Tao

    2017-02-01

    We have investigated the influence of nanohole size on selective-area growth (SAG) of InAs nanowire (NW) arrays on Si(111) substrates by metal-organic chemical vapor deposition. The growth of well-defined and position-controlled InAs NW arrays with united vertical orientation can be achieved on the patterned substrates with a certain range of nanohole size, which paves the way for the fabrication of high-electron-mobility and surrounding-gate transistor arrays using NWs as channels. Moreover, it is found that more than one NW are increasingly likely grown per nanohole as the nanohole size increases, and the NWs become increasingly thin and short. This is considered to be due to the supersaturation of adsorbed species in the nanohole and the intense competition for adatoms among multiple NWs per nanohole.

  14. Characteristics of highly stacked InAs quantum-dot laser grown on vicinal (001)InP substrate

    Science.gov (United States)

    Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Yamamoto, Naokatsu; Kawanishi, Tetsuya

    2016-04-01

    We fabricate broad-area laser diodes consisting of 30-layer stacks of InAs quantum dots by using a strain-compensation technique on a vicinal (001)InP substrate. These laser diodes exhibit ground-state lasing at 1576 nm in the pulsed mode with a high characteristic temperature of 111 K at around room temperature (20-80 °C).

  15. Improved dot size uniformity and luminescense of InAs quantum dots on InP substrate

    Science.gov (United States)

    Qiu, Y.; Uhl, D.

    2002-01-01

    InAs self-organized quantum dots have been grown in InGaAs quantum well on InP substrates by metalorganic vapor phase epitaxy. Atomic Force Microscopy confirmed of quantum dot formation with dot density of 3X10(sup 10) cm(sup -2). Improved dot size uniformity and strong room temperature photoluminescence up to 2 micron were observed after modifying the InGaAs well.

  16. Superconducting transport in single and parallel double InAs quantum dot Josephson junctions with Nb-based superconducting electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shoji, E-mail: baba@meso.t.u-tokyo.ac.jp; Sailer, Juergen [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Deacon, Russell S. [Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama 351-0198 (Japan); RIKEN Advanced Science Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Oiwa, Akira [The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Shibata, Kenji [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Department of Electronics and Intelligent Systems, Tohoku Institute of Technology, Sendai 982-8577 (Japan); Hirakawa, Kazuhiko [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); JST CREST, 4-1-8 Hon-cho, Kawaguchi-shi, Saitama 332-0012 (Japan); Tarucha, Seigo [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama 351-0198 (Japan); INQIE, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); QPEC, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku 113-8656 (Japan)

    2015-11-30

    We report conductance and supercurrent measurements for InAs single and parallel double quantum dot Josephson junctions contacted with Nb or NbTiN superconducting electrodes. Large superconducting gap energy, high critical field, and large switching current are observed, all reflecting the features of Nb-based electrodes. For the parallel double dots, we observe an enhanced supercurrent when both dots are on resonance, which may reflect split Cooper pair tunneling.

  17. Evidence for two-dimensional spin-glass ordering in submonolayer Fe films on cleaved InAs surfaces.

    Science.gov (United States)

    Mochizuki, Toshimitsu; Masutomi, Ryuichi; Okamoto, Tohru

    2008-12-31

    Magnetotransport measurements have been performed on two-dimensional electron gases formed at InAs(110) surfaces covered with a submonolayer of Fe. Hysteresis in the magnetoresistance, a difference in remanent magnetoresistance between zero-field-cooling procedures and field-cooling procedures, and logarithmic time-dependent relaxation after magnetic field sweep are clearly observed at 1.7 K for a coverage of 0.42 monolayer. These features are associated with spin-glass ordering in the Fe film.

  18. Growth and anisotropic transport properties of self-assembled InAs nanostructures in InP

    Energy Technology Data Exchange (ETDEWEB)

    Bierwagen, O.

    2007-12-20

    Self-assembled InAs nanostructures in InP, comprising quantum wells, quantum wires, and quantum dots, are studied in terms of their formation and properties. In particular, the structural, optical, and anisotropic transport properties of the nanostructures are investigated. The focus is a comprehending exploration of the anisotropic in-plane transport in large ensembles of laterally coupled InAs nanostructures. The self-assembled Stranski-Krastanov growth of InAs nanostructures is studied by gas-source molecular beam epitaxy on both nominally oriented and vicinal InP(001). Optical polarization of the interband transitions arising from the nanostructure type is demonstrated by photoluminescence and transmission spectroscopy. The experimentally convenient four-contact van der Pauw Hall measurement of rectangularly shaped semiconductors, usually applied to isotropic systems, is extended to yield the anisotropic transport properties. Temperature dependent transport measurements are performed in large ensembles of laterally closely spaced nanostructures. The transport of quantum wire-, quantum dash- and quantum dot containing samples is highly anisotropic with the principal axes of conductivity aligned to the <110> directions. The direction of higher mobility is [ anti 110], which is parallel to the direction of the quantum wires. In extreme cases, the anisotropies exceed 30 for electrons, and 100 for holes. The extreme anisotropy for holes is due to diffusive transport through extended states in the [ anti 110], and hopping transport through laterally localized states in the [110] direction, within the same sample. A novel 5-terminal electronic switching device based on gate-controlled transport anisotropy is proposed. The gate-control of the transport anisotropy in modulation-doped, self-organized InAs quantum wires embedded in InP is demonstrated. (orig.)

  19. Adding GaAs Monolayers to InAs Quantum-Dot Lasers on (001) InP

    Science.gov (United States)

    Qiu, Yueming; Chacon, Rebecca; Uhl, David; Yang, Rui

    2005-01-01

    In a modification of the basic configuration of InAs quantum-dot semiconductor lasers on (001)lnP substrate, a thin layer (typically 1 to 2 monolayer thick) of GaAs is incorporated into the active region. This modification enhances laser performance: In particular, whereas it has been necessary to cool the unmodified devices to temperatures of about 80 K in order to obtain lasing at long wavelengths, the modified devices can lase at wavelengths of about 1.7 microns or more near room temperature. InAs quantum dots self-assemble, as a consequence of the lattice mismatch, during epitaxial deposition of InAs on ln0.53Ga0.47As/lnP. In the unmodified devices, the quantum dots as thus formed are typically nonuniform in size. Strainenergy relaxation in very large quantum dots can lead to poor laser performance, especially at wavelengths near 2 microns, for which large quantum dots are needed. In the modified devices, the thin layers of GaAs added to the active regions constitute potential-energy barriers that electrons can only penetrate by quantum tunneling and thus reduce the hot carrier effects. Also, the insertion of thin GaAs layer is shown to reduce the degree of nonuniformity of sizes of the quantum dots. In the fabrication of a batch of modified InAs quantum-dot lasers, the thin additional layer of GaAs is deposited as an interfacial layer in an InGaAs quantum well on (001) InP substrate. The device as described thus far is sandwiched between InGaAsPy waveguide layers, then further sandwiched between InP cladding layers, then further sandwiched between heavily Zn-doped (p-type) InGaAs contact layer.

  20. Visible Light-Assisted High-Performance Mid-Infrared Photodetectors Based on Single InAs Nanowire.

    Science.gov (United States)

    Fang, Hehai; Hu, Weida; Wang, Peng; Guo, Nan; Luo, Wenjin; Zheng, Dingshan; Gong, Fan; Luo, Man; Tian, Hongzheng; Zhang, Xutao; Luo, Chen; Wu, Xing; Chen, Pingping; Liao, Lei; Pan, Anlian; Chen, Xiaoshuang; Lu, Wei

    2016-10-12

    One-dimensional InAs nanowires (NWs) have been widely researched in recent years. Features of high mobility and narrow bandgap reveal its great potential of optoelectronic applications. However, most reported work about InAs NW-based photodetectors is limited to the visible waveband. Although some work shows certain response for near-infrared light, the problems of large dark current and small light on/off ratio are unsolved, thus significantly restricting the detectivity. Here in this work, a novel "visible light-assisted dark-current suppressing method" is proposed for the first time to reduce the dark current and enhance the infrared photodetection of single InAs NW photodetectors. This method effectively increases the barrier height of the metal-semiconductor contact, thus significantly making the device a metal-semiconductor-metal (MSM) photodiode. These MSM photodiodes demonstrate broadband detection from less than 1 μm to more than 3 μm and a fast response of tens of microseconds. A high detectivity of ∼10(12) Jones has been achieved for the wavelength of 2000 nm at a low bias voltage of 0.1 V with corresponding responsivity of as much as 40 A/W. Even for the incident wavelength of 3113 nm, a detectivity of ∼10(10) Jones and a responsivity of 0.6 A/W have been obtained. Our work has achieved an extended detection waveband for single InAs NW photodetector from visible and near-infrared to mid-infrared. The excellent performance for infrared detection demonstrated the great potential of narrow bandgap NWs for future infrared optoelectronic applications.

  1. Historical Survey of Nuclear Non-Proliferation Treaty%《不扩散核武器条约》的历史审视

    Institute of Scientific and Technical Information of China (English)

    费赫夫

    2012-01-01

    Although Nuclear Non-Proliferation Treaty is a product of power politics, it objectively plays an active role in the prevention of nuclear proliferation. As the foundation stone of nuclear non-proliferation regime, the treaty has experienced a lot of severe tests and nowadays is facing many challenges, which will have a bright future. In order to achieve the goal of Nuclear Non-Proliferation Treaty, nuclear disarmament and the right of non-nuclear states to peacefully use nuclear energy should be paid more attention in the future. Only in this way can the glorious desire of nuclear-free world be realized.%《不扩散核武器条约》虽然是强权政治的产物,但它在客观上为防止核扩散起着积极作用,是核不扩散体制的基石。该条约经历了许多严峻的考验,当今也面临不少的挑战,不扩散核武器条约的未来还是美好的。为了实现不扩散核武器条约的目标,今后更应关注核裁军和无核国家和平利用核能的权利。只有这样,无核世界的美好愿望才能实现。

  2. Short-wavelength infrared photodetector on Si employing strain-induced growth of very tall InAs nanowire arrays.

    Science.gov (United States)

    Shin, Hyun Wook; Lee, Sang Jun; Kim, Doo Gun; Bae, Myung-Ho; Heo, Jaeyeong; Choi, Kyoung Jin; Choi, Won Jun; Choe, Jeong-woo; Shin, Jae Cheol

    2015-06-02

    One-dimensional crystal growth enables the epitaxial integration of III-V compound semiconductors onto a silicon (Si) substrate despite significant lattice mismatch. Here, we report a short-wavelength infrared (SWIR, 1.4-3 μm) photodetector that employs InAs nanowires (NWs) grown on Si. The wafer-scale epitaxial InAs NWs form on the Si substrate without a metal catalyst or pattern assistance; thus, the growth is free of metal-atom-induced contaminations, and is also cost-effective. InAs NW arrays with an average height of 50 μm provide excellent anti-reflective and light trapping properties over a wide wavelength range. The photodetector exhibits a peak detectivity of 1.9 × 10(8) cm · Hz(1/2)/W for the SWIR band at 77 K and operates at temperatures as high as 220 K. The SWIR photodetector on the Si platform demonstrated in this study is promising for future low-cost optical sensors and Si photonics.

  3. Quantum Dots obtained by LPE from under-saturated In-As liquid phases on GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz F E; Mishurnyi V; Gorbatchev A; De Anda F [Universidad Autonoma de San Luis Potosi, Instituto de Investigacion en Comunicacion Optica, Av. Karacorum 1470, Col. Lomas 4a Sec., CP 78210San Luis PotosI (Mexico); Prutskij T, E-mail: fcoe_ov@prodigy.net.mx, E-mail: andre@cactus.iico.uaslp.mx [BUAP, Instituto de Ciencias, Apartado Postal 207, 72000, Puebla (Mexico)

    2011-01-01

    In this work we inform about quantum dots (QD) obtained by Liquid Phase Epitaxy (LPE) on GaAs substrates from under-saturated In-As liquid phases. In our processes, we have prepared saturated In-rich liquid phases by dissolving an InAs wafer at one of the temperatures interval from 450 to 414 C for 60 minutes. The contact between In-As liquid phase and the GaAs substrate was always done at a constant temperature of 444 C for 5 seconds. Thus, the growth temperature for most of the samples was higher than the liquidus temperature. We think that the growth driving force is related to a transient process that occurs when the system is trying to reach equilibrium. Under the atom force microscope (AFM) we have observed nano-islands on the surfaces of the samples obtained from under-saturated liquid phases prepared at 438, 432 and 426 C. The 25 K photoluminescence spectrum shows a peak at a 1.33 eV, in addition to the GaAs related line.

  4. Optical investigation of InAs quantum dots inserted in AlGaAs/GaAs modulation doped heterostructure

    Science.gov (United States)

    Khmissi, H.; Baira, M.; Sfaxi, L.; Bouzaïene, L.; Saidi, F.; Bru-Chevallier, C.; Maaref, H.

    2011-03-01

    Optical properties of InAs quantum dots (QDs) inserted in AlGaAs/GaAs modulation doped heterostructure are investigated. To study the effect of carrier transfer behavior on the luminescence of self-assembled quantum dots, a series of sample has been prepared using molecular beam epitaxy (Riber 32 system) in which we have varied the thickness separating the delta dopage and the InAs quantum dots layer. Photoluminescence spectra show the existence of two peaks that can be attributed to transition energies from the ground state (E1-HH1) and the first excited state (E2-HH2). Two antagonist effects have been observed, a blue shift of the emission energies result from electron transferred from the AlGaAs/GaAs heterojunction to the InAs quantum dots and a red shift caused by the quantum confined Stark effect due to the internal electric field existing In the AlGaAs/GaAs heterojunction.

  5. Current resonances and current platforms in a two-level InAs quantum dot with asymmetric terahertz irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, R.-Y., E-mail: yuanry@cnu.edu.cn [Center for Theoretical Physics, Department of Physics, Capital Normal University, Beijing 100048 (China); Zhao, X.; Ji, A.-C. [Center for Theoretical Physics, Department of Physics, Capital Normal University, Beijing 100048 (China); Guo, Y., E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Yan, H. [Laboratory of Thin Film Materials, Beijing University of Technology, Beijing 100022 (China)

    2015-09-04

    Both the charging and orbital quantization energies of InAs quantum dot (QD) typically correspond to the terahertz (THz) region. In this letter, under the asymmetric THz irradiations on two leads, electron transport through a two-level InAs QD is theoretically discussed. We demonstrate that when both the frequencies and amplitudes of THz irradiations on two leads are different with the higher asymmetry, the photon–electron pump effect vanishes, even a negative platform appears on the left of the Coulomb peak and a positive platform occurs on the right of the Coulomb interaction related energy level, respectively. This behavior is favorable for the design of THz optoelectronic device. - Highlights: • Asymmetric terahertz waves are irradiated on two leads in two-level InAs QD system. • Only with different frequencies, a negative current resonance is obtained. • A negative platform appears on the left of the Coulomb peak with higher asymmetry. • For the low terahertz field strength, a positive platform occurs. • We report the behaviors are favorable for the design of THz optoelectronic device.

  6. High performance InAs quantum dot lasers on silicon substrates by low temperature Pd-GaAs wafer bonding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zihao; Preble, Stefan F. [Microsystems Engineering, Rochester Institute of Technology, Rochester, New York 14623 (United States); Yao, Ruizhe; Lee, Chi-Sen; Guo, Wei, E-mail: wei-guo@uml.edu [Physics and Applied Physics Department, University of Massachusetts Lowell, Lowell, Massachusetts 01854 (United States); Lester, Luke F. [Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

    2015-12-28

    InAs quantum dot (QD) laser heterostructures have been grown by molecular beam epitaxy system on GaAs substrates, and then transferred to silicon substrates by a low temperature (250 °C) Pd-mediated wafer bonding process. A low interfacial resistivity of only 0.2 Ω cm{sup 2} formed during the bonding process is characterized by the current-voltage measurements. The InAs QD lasers on Si exhibit comparable characteristics to state-of-the-art QD lasers on silicon substrates, where the threshold current density J{sub th} and differential quantum efficiency η{sub d} of 240 A/cm{sup 2} and 23.9%, respectively, at room temperature are obtained with laser bars of cavity length and waveguide ridge of 1.5 mm and 5 μm, respectively. The InAs QD lasers also show operation up to 100 °C with a threshold current density J{sub th} and differential quantum efficiency η{sub d} of 950 A/cm{sup 2} and 9.3%, respectively. The temperature coefficient T{sub 0} of 69 K from 60 to 100 °C is characterized from the temperature dependent J{sub th} measurements.

  7. Phase diagrams for understanding gold-seeded growth of GaAs and InAs nanowires

    Science.gov (United States)

    Ghasemi, Masoomeh; Johansson, Jonas

    2017-04-01

    Phase diagrams are useful tools to study the phase equilibria of nanowire materials systems because the growth of nanowires is accompanied by phase formation and phase transition. We have modeled the phase equilibria of the As–Au–Ga ternary system by means of the CALPHAD method. This method is a well-established semi-empirical technique for thermodynamic modeling in which Gibbs energy functions with free parameters are defined for all phases in a system followed by adjusting these parameters to the experimental data. Using the resulting As–Au–Ga thermodynamic database, four vertical cuts of this ternary system are calculated and all show good agreement with experiments. This ternary system is particularly useful for predicting the state of the Au seed alloys when growing GaAs nanowires and we discuss such predictions. Similar calculations are performed for Au-seeded InAs nanowires. We show that the vapor–liquid–solid (VLS) growth fails for InAs nanowires, while GaAs nanowires can grow from a liquid particle. Our calculations are in agreement with experimental data on the growth of Au-seeded GaAs and InAs nanowires.

  8. Reciprocal modulation of IK1-INa extends excitability in cardiac ventricular cells

    Directory of Open Access Journals (Sweden)

    Anthony Varghese

    2016-11-01

    Full Text Available The inwardly rectifying potassium current (IK1 and the fast inward sodium current (INa are reciprocally modulated in mammalian ventricular myocytes. An increase in the expression of channels responsible for one of these two currents results in a corresponding increase in expression of the other. These currents are critical in the propagation of action potentials (AP during the normal functioning of the heart. This study identifies a physiological role for IK1-INa reciprocal modulation in ventricular fiber activation thresholds and conduction. Simulations of action potentials in single cells and propagating APs in cardiac fibers were carried out using an existing model of electrical activity in cardiac ventricular myocytes. The conductances, GK1, of the inwardly rectifying potassium current, and GNa, of the fast inward sodium current were modified independently and in tandem to simulate reciprocal modulation. In single cells, independent modulation of GK1 alone resulted in changes in activation thresholds that were qualitatively similar to those for reciprocal GK1-GNa modulation and unlike those due to independent modulation of GNa alone, indicating that GK1 determines the cellular activation threshold. On the other hand, the variations in conduction velocity in cardiac cell fibers were similar for independent GNa modulation and for tandem changes in GK1-GNa, suggesting that GNa is primarily responsible for setting tissue AP conduction velocity. Conduction velocity dependence on GK1-GNa is significantly affected by the intercellular gap junction conductance. While the effects on the passive fiber space constant due to changes in both GK1 and the intercellular gap junction conductance, Ggj, were in line with linear cable theory predictions, both conductances had surprisingly large effects on fiber activation thresholds. Independent modulation of GK1 rendered cardiac fibers inexcitable at higher levels of GK1 whereas tandem GK1-GNa changes allowed

  9. Nuclear proliferation and civilian nuclear power. Report of the Nonproliferation Alternative Systems Assessment Program. Volume IX. Reactor and fuel cycle description

    Energy Technology Data Exchange (ETDEWEB)

    1980-06-01

    The Nonproliferation Alterntive Systems Assessment Program (NASAP) has characterized and assessed various reactor/fuel-cycle systems. Volume IX provides, in summary form, the technical descriptions of the reactor/fuel-cycle systems studied. This includes the status of the system technology, as well as a discussion of the safety, environmental, and licensing needs from a technical perspective. This information was then used in developing the research, development, and demonstration (RD and D) program, including its cost and time frame, to advance the existing technology to the level needed for commercial use. Wherever possible, the cost data are given as ranges to reflect the uncertainties in the estimates.

  10. Molecular Characterization of an Ice Nucleation Protein Variant (InaQ from Pseudomonas syringae and the Analysis of Its Transmembrane Transport Activity in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Qianqian Li, Qi Yan, Jinsi Chen, Yan He, Jing Wang, Hongxing Zhang, Ziniu Yu, Lin Li

    2012-01-01

    Full Text Available The ice nucleation protein (INP of Pseudomonas syringae has gained scientific interest not only because of its pathogenicity of foliar necroses but also for its wide range of potential applications, such as in snow making, frozen food preparation, and surface-display system development. However, studies on the transport activity of INP remain lacking. In the present study, a newly identified INP-gene variant, inaQ, from a P. syringae MB03 strain was cloned. Its structural domains, signal sequences, and the hydrophilicity or hydrophobicity of each domain, were then characterized. The deduced amino acid sequence of InaQ shares similar protein domains with three P. syringae INPs, namely, InaK, InaZ, and InaV, which were identified as an N-terminal domain, a central repeating domain, and a C-terminal domain. The expression of the full-length InaQ and of various truncated variants was induced in Escherichia coli to analyze their transmembrane transport and surface-binding activities, while using the green fluorescence protein (GFP as the fusion partner. With two transmembrane segments and a weak secretion signal, the N-terminal domain (InaQ-N alone was found to be responsible for the transport process as well as for the binding to the outer membrane, whereas the C-terminal region was nonfunctional in protein transport. Increased membrane transport and surface-binding capacities were induced by a low isopropyl-β-D-thiogalactoside concentration (0.1 mmol/l but not by culture temperatures (15 ºC to 37 ºC. Furthermore, by constructing the GFP-fused proteins with a single InaQ-N, as well as two and three tandemly aligned InaQ-N molecules, the transport and membrane-binding activities of these proteins were compared using Western blot analysis, immmunofluorescence microscopy, and assays of the GFP specific fluorescence intensity of subcellular fractions and flow cytometry, which showed that the increase of InaQ-N repeats resulted in a coordinated

  11. Molecular characterization of an ice nucleation protein variant (inaQ) from Pseudomonas syringae and the analysis of its transmembrane transport activity in Escherichia coli.

    Science.gov (United States)

    Li, Qianqian; Yan, Qi; Chen, Jinsi; He, Yan; Wang, Jing; Zhang, Hongxing; Yu, Ziniu; Li, Lin

    2012-01-01

    The ice nucleation protein (INP) of Pseudomonas syringae has gained scientific interest not only because of its pathogenicity of foliar necroses but also for its wide range of potential applications, such as in snow making, frozen food preparation, and surface-display system development. However, studies on the transport activity of INP remain lacking. In the present study, a newly identified INP-gene variant, inaQ, from a P. syringae MB03 strain was cloned. Its structural domains, signal sequences, and the hydrophilicity or hydrophobicity of each domain, were then characterized. The deduced amino acid sequence of InaQ shares similar protein domains with three P. syringae INPs, namely, InaK, InaZ, and InaV, which were identified as an N-terminal domain, a central repeating domain, and a C-terminal domain. The expression of the full-length InaQ and of various truncated variants was induced in Escherichia coli to analyze their transmembrane transport and surface-binding activities, while using the green fluorescence protein (GFP) as the fusion partner. With two transmembrane segments and a weak secretion signal, the N-terminal domain (InaQ-N) alone was found to be responsible for the transport process as well as for the binding to the outer membrane, whereas the C-terminal region was nonfunctional in protein transport. Increased membrane transport and surface-binding capacities were induced by a low isopropyl-β-D-thiogalactoside concentration (0.1 mmol/l) but not by culture temperatures (15 ºC to 37 ºC). Furthermore, by constructing the GFP-fused proteins with a single InaQ-N, as well as two and three tandemly aligned InaQ-N molecules, the transport and membrane-binding activities of these proteins were compared using Western blot analysis, immmunofluorescence microscopy, and assays of the GFP specific fluorescence intensity of subcellular fractions and flow cytometry, which showed that the increase of InaQ-N repeats resulted in a coordinated increase of the

  12. Electrical characterization of chemical and dielectric passivation of InAs nanowires

    Science.gov (United States)

    Holloway, Gregory W.; Haapamaki, Chris M.; Kuyanov, Paul; LaPierre, Ray R.; Baugh, Jonathan

    2016-11-01

    The native oxide at the surface of III-V nanowires, such as InAs, can be a major source of charge noise and scattering in nanowire-based electronics, particularly for quantum devices operated at low temperatures. Surface passivation provides a means to remove the native oxide and prevent its regrowth. Here, we study the effects of surface passivation and conformal dielectric deposition by measuring electrical conductance through nanowire field effect transistors treated with a variety of surface preparations. By extracting field effect mobility, subthreshold swing, threshold shift with temperature, and the gate hysteresis for each device, we infer the relative effects of the different treatments on the factors influencing transport. It is found that a combination of chemical passivation followed by deposition of an aluminum oxide dielectric shell yields the best results compared to the other treatments, and comparable to untreated nanowires. Finally, it is shown that an entrenched, top-gated device using an optimally treated nanowire can successfully form a stable double quantum dot at low temperatures. The device has excellent electrostatic tunability owing to the conformal dielectric layer and the combination of local top gates and a global back gate.

  13. Fundamental interface studies of GaSb and InAs substrates with atomic layer deposition

    Science.gov (United States)

    Greer, Frank; Baker, L.; Cook, S.; Fisher, A.; Keo, S.; Soibel, A.; Khoshakhlagh, Arezou; Nguyen, J.; Ting, D.; Gunapala, S.

    2012-10-01

    Long Wavelength infrared photodetectors based on Type-II superlattices from the 6.1Å system hold great promise for a wide variety of applications. However, as these materials are fabricated into focal plane arrays for real world applications, the small pixel sizes that are required can result in unacceptably high dark current due to a significant contribution of surface-induced leakage. These surface currents could be substantially reduced or even eliminated by the application of an appropriate passivation material. But, while a considerable amount of effort has gone into developing passivation processes and materials for these detectors (e.g. PECVD SiO2, polyimides, etc.), there is no one widely adopted standard technique in use today. Atomic layer deposition has the possibility of being an excellent method for depositing passivation because of the wide variety of materials that are readily available via ALD and the ability to conformally coat arbitrary topographies that may be found in the patterning of LWIR FPAs. In this work, fundamental materials characterization results and electrical test data will be presented for two wide band gap, high-K dielectrics (Titanium Oxide and Hafnium Oxide) looking at their nucleation and growth behavior on substrates of relevant III-V materials such as GaSb and InAs using ellispometry, XPS, and XRD. These results will be compared to more conventional passivation strategies to highlight the unique features of the ALD technique.

  14. Measuring surface state density and energy distribution in InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Halpern, Eliezer; Cohen, Gilad; Gross, Shahar; Henning, Alexander; Matok, Max; Rosenwaks, Yossi [Department of Physical Electronics, School of Electrical Engineering, Tel-Aviv University (Israel); Kretinin, Andrey V. [School of Physics and Astronomy, University of Manchester (United Kingdom); Shtrikman, Hadas [Department of Condensed Matter Physics, Braun Center for Submicrometer Research, Weizmann Institute of Science, Rehovot (Israel)

    2014-02-15

    Semiconducting nanowires are expected to have applications in various areas as transistors, sensors, resonators, solar cells, and thermoelectric systems. Understanding the surface properties is crucial for the fabrication of high-performance devices. Due to the large surface-to-volume ratio of nanowires, their surface electronic properties, like surface states, can a have a large effect on the performance of both electronic and optoelectronic devices. At present, determination of the surface state density depends on a combination of experimental measurements of the capacitance and/or drain current, in a nanowire field-effect transistor, and a fitting to simulation. This technique follows certain assumptions, which can severely harm the accuracy of the extracted density of states. In this report, we demonstrate a direct measurement of the surface state density of individual InAs and silicon nanowires. The method is based on measuring the surface potential of a nanowire field-effect transistor, with respect to a changing gate bias. The extracted density of states at the surface helps to explain various electronic phenomena in such devices. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Comparison of InAs nanowire conductivity: influence of growth method and structure

    Energy Technology Data Exchange (ETDEWEB)

    Sladek, Kamil; Winden, Andreas; Wirths, Stephan; Weis, Karl; Bloemers, Christian; Guel, Oender; Grap, Thomas; Lenk, Steffi; Ahe, Martina van der; Hardtdegen, Hilde; Lepsa, Mihail Ion; Lueth, Hans; Schaepers, Thomas; Gruetzmacher, Detlev [Peter Gruenberg Institut (PGI-9), Forschungszentrum Juelich (Germany); Juelich Aachen Research Alliance (JARA) (Germany); Weirich, Thomas E. [Juelich Aachen Research Alliance (JARA) (Germany); Central Facility for Electron Microscopy (GFE), Institute of Crystallography, RWTH Aachen University (Germany); Lysov, Andrey; Li, Zi-An; Prost, Werner; Tegude, Franz-Josef [Center for Nanointegration, University of Duisburg-Essen, Duisburg (Germany)

    2012-02-15

    The conductivity and crystal structure of nominally undoped InAs nanowires deposited by three different methods - 1. selective area metal organic vapor phase epitaxy (SA MOVPE), 2. gold assisted vapor liquid solid (VLS) MOVPE and 3. extrinsic catalyst free VLS molecular beam epitaxy (MBE) - is investigated. The influence on conductivity by stacking faults and different growth conditions is analyzed to determine the main impact. It is found that in terms of crystal structure, nanowires deposited by VLS MOVPE and VLS MBE behave similarly showing a zinc blende (ZB) phase while nanowires deposited by SA MOVPE feature a high density of stacking faults and a tendency to higher amounts of wurtzite (WZ) when grown with a decreased growth rate. However, the conductivity of wires deposited by VLS MOVPE is found to be much higher and statistically less dispersive compared to the other two wire types. An electrical similarity between nominally undoped wires in VLS MOVPE and previously reported intentionally doped wires in SA MOVPE is observed and discussed. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Some reasons of emission variation in InAs quantum dot-in-a-well structures

    Science.gov (United States)

    Torchynska, T. V.; Palacios Gomez, J.; Gómez Gasga, G.; Vivas Hernandez, A.; Velazquez Lozada, E.; Polupan, G.; Shcherbyna, Ye S.

    2010-09-01

    Photoluminescence (PL) and X ray diffraction have been studied in InAs quantum dots (QDs) embedded in symmetric In0.15Ga1-0.15As/GaAs quantum wells (dot-in-a-well, DWELL) with QDs grown at different temperatures. The density of QDs decreases from 1.1×1011 down to 1.3×1010 cm-2 with increasing the QD growth temperatures from 470 to 535°C. The QD density decreasing in DWELLs is accompanied by the non monotonous variation of QD parameters. The PL intensity increases and the PL peak shifts to low energy in structures with QDs grown at 490 and 510°C. On the contrary the structures with QDs grown at 525 and 535°C are characterized by lower PL intensities and PL peak positions shifted to higher energy. The method of X-ray diffraction has been applied with the aim to study the variation of elastic strain in DWELL structures with QDs grown at different temperatures. It was shown that the minimum of elastic strain corresponds to DWELL with QDs grown at 490-525 °C. For lower (470 °C) and higher (535 °C) QD growth temperatures the level of compressive strain increased in DWELLs. The reasons of strain variation are discussed as well.

  17. THE GRAPHEMES ОУ, Ѫ, Ю AND Ѭ IN IL’INA KNIGA

    Directory of Open Access Journals (Sweden)

    Igor M. Ladyzhensky

    2015-01-01

    Full Text Available The article examines the usage of graphemes ѹ, ю, ѫ, ѭ in Il’ina kniga (Russian State Archive, F.381, No. 131. Regularities of using these graphemes provide evidence for the existence of certain spelling rules. For example, scribe Ilya never uses ѭ after consonants (in this position only ю is used, and ѫ very seldom appears at the beginning of words or after vowels. On the whole Ilya preferred to write ѫ in roots and the digraph оу in inflections. He quite consistently associated some roots with grapheme ѫ, and ѫ-marking could extend to homophonous roots (thus, under the influence of the root лѫк- the words прилоучитися, оулоучити, лѹча and the comparative лѹчии were written in most cases with jus. 

  18. Extreme Harmonic Generation in an InAs Spin-Orbit Qubit

    Science.gov (United States)

    Stehlik, J.; Schroer, M. D.; Maialle, M. Z.; Degani, M. H.; Petta, J. R.

    2014-03-01

    Strong spin-orbit materials have shown great promise in the field of quantum computation. Unlike conventional semiconductor materials, fast all-electrical control is achieved through electric dipole spin resonance (EDSR). In this work we explore EDSR in an InAs nanowire spin-orbit qubit. We observe signs of harmonic generation where spin flips occur at the resonance condition nhf = gμB B , where f is the applied frequency, B is the magnetic field, g is the g-factor and n is an integer. Near the interdot charge transition we observe harmonics up to n = 8, indicating extreme harmonic generation. At far detuning we only observe the n = 1 resonance. Further, we find odd/even structure in the harmonic response: odd harmonics result in an increase in the leakage current while even harmonics result in its suppression. Finally we observe oscillations in the resonant current as a function of detuning. The striking detuning dependence suggests that the harmonics may be caused by Landau-Zener transitions occurring due to the anti-crossing between the differing charge states. Numerical simulations of the system are qualitatively consistent with this picture. Funded by the Sloan and Packard Foundations, the NSF, and the Army Research Office. M.Z.M. and M.H.D. were funded by Fundação de Amparo à Pesquisa de São Paulo (Fapesp) and INCT-DISSE/CNPq, Brazil.

  19. High-Mobility GaSb Nanostructures Cointegrated with InAs on Si.

    Science.gov (United States)

    Borg, Mattias; Schmid, Heinz; Gooth, Johannes; Rossell, Marta D; Cutaia, Davide; Knoedler, Moritz; Bologna, Nicolas; Wirths, Stephan; Moselund, Kirsten E; Riel, Heike

    2017-02-22

    GaSb nanostructures integrated on Si substrates are of high interest for p-type transistors and mid-IR photodetectors. Here, we investigate the MOCVD growth and properties of GaSb nanostructures monolithically integrated onto silicon-on-insulator wafers using template-assisted selective epitaxy. A high degree of morphological control allows for GaSb nanostructures with critical dimensions down to 20 nm. Detailed investigation of growth parameters reveals that the GaSb growth rate is governed by the desorption processes of an Sb surface, and in turn is insensitive to changes in material transport efficiency. The GaSb crystal structure is typically zinc-blende with a low density of rotational twin defects and even occasional twin-free structures are observed. Van der Pauw/Hall measurements are conducted on 20 nm thick GaSb nanostructures, revealing high hole mobility of 760 cm2/Vs, which matches literature values for high-quality bulk GaSb crystals. Finally, we demonstrate a process that enables cointegration of GaSb and InAs nanostructures in close vicinity on Si, a preferred material combination ideally suited for high-performance complementary III-V MOS technology.

  20. Tunable double quantum dots in InAs nanowires defined by local gate electrodes.

    Science.gov (United States)

    Fasth, Carina; Fuhrer, Andreas; Samuelson, Lars

    2006-03-01

    We present low-temperature transport measurements on quantum dots induced in homogeneous InAs quantum wires 50 nm in diameter. Quantum dots are induced by electrical depletion of the wire using local gate electrodes with down to 30 nm electrode spacing. This scheme has permitted the realization of fully gate-defined multiple quantum dots along the nanowire [1]. Tunability in double quantum dots is a prerequisite for the system to be operated as a quantum gate. We demonstrate control over the lead tunnel barrier transparencies and, in the case of double quantum dots, the interdot coupling. Using the local gate electrodes also as plunger gates we measure double dot honeycomb stability diagrams which show the transition from a single large dot to two weakly coupled dots at 4.2K. The induced quantum dots can be tuned into the few-electron regime which is shown from Coulomb blockade measurements. We extract values of orbital energy-level spacings, capacitances and capacitive and tunnel interdot coupling for this system. [1] C. Fasth et al., NanoLett 5, 1487 (2005).

  1. Fabrication and optical properties of multishell InAs quantum dots on GaAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Xin; Zhang, Xia, E-mail: xzhang@bupt.edu.cn; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2015-02-07

    Hybrid nanostructures combining nanowires with quantum dots promote the development of nanoelectronic and nanophotonic devices with integrated functionalities. In this work, we present a complex nanostructure with multishell quantum dots grown on nanowires. 1–4 shells of Stranski-Krastanov InAs quantum dots are grown on the sidewalls of GaAs nanowires by metal organic chemical vapor deposition. Different dot shells are separated by 8 nm GaAs spacer shells. With increasing the number of shells, the quantum dots become sparser and tend to align in one array, which is caused by the shrinkage of facets on which dots prefer to grow as well as the strain fields produced by the lower set of dots which influences the migration of In adatoms. The size of quantum dots increases with the increase of shell number due to enhanced strain fields coupling. The spectra of multishell dots exhibit multiwavelength emission, and each peak corresponds to a dot shell. This hybrid structure may serve as a promising element in nanowire intermediate band solar cells, infrared nanolasers, and photodetectors.

  2. Ambient temperature dependence on emission spectrum of InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, C.Y.; Yoon, S.F. [School of Electrical and Electronic Engineering, Nanyang Technological University (Singapore); Chua, S.J. [Institute of Materials Research and Engineering, Faculty of Engineering (Singapore)

    2009-04-15

    Semiconductor superluminescent diodes (SLDs) are important broadband light source for fiber optic gyroscope and biomedical imaging. Quantum dots (QDs) have been proposed to be the best candidate for broadband light sources due to the inhomogeneous broadening of the gain spectrum as a result of the inherited size inhomogeneity of the self-assembled QD growth. In this work, the effect of ambient temperature (25-100 C) on the emission spectrum of InAs QDs with wideband emission was investigated. It was found that the full-width at half-maximum (FWHM) of the photoluminescence (PL) spectra remains more than 125 nm throughout the temperature range, and the redshift as function of temperature is approximately 0.27 meV/K. Activation energy of 270 meV is extracted from the Arrhenius plot and the PL quenching at high temperature is attributed to thermally induced carriers escaping out of the In{sub 0.15}Ga{sub 0.85}As strain-reducing layer. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. The effective excitonic g factors of Mn-doped InAs nanowires

    Science.gov (United States)

    Xiong, Wen

    2017-04-01

    Based on the derived eight-band k · p Hamiltonian, the electronic structures of Mn-doped InAs nanowires in the magnetic field are calculated. We find the lowest optical transition will be split to four individual transitions when the magnetic field is applied along z axis, and two of them are σ polarized light. Furthermore, the Zeeman splitting energy at the Γ point of two σ polarized light will increase nonlinearly as the increase of the magnetic field. Additionally, an effective excitonic g factor at the Γ point is defined, and the effective excitonic g factors will decrease greatly with the increase of the radius of nanowires and the decrease of the concentration of manganese ions, while the effective excitonic g factors decrease slightly when the magnetic field increases. Interestingly, the effective excitonic g factors can experience a substantial decrease when the temperature increases from 10 K to 100 K and is almost not affected when the temperature varies from 100 K to 300 K. Therefore, we can infer that large effective excitonic g factors can be obtained when small radius of nanowires, high concentration of manganese ions and low temperature are satisfied.

  4. Excitonic fine structure and binding energies of excitonic complexes in single InAs quantum dashes

    Science.gov (United States)

    Mrowiński, P.; Zieliński, M.; Świderski, M.; Misiewicz, J.; Somers, A.; Reithmaier, J. P.; Höfling, S.; Sek, G.

    2016-09-01

    The fundamental electronic and optical properties of elongated InAs nanostructures embedded in quaternary InGaAlAs barrier are investigated by means of high-resolution optical spectroscopy and many-body atomistic tight-binding theory. These wire-like shaped, self-assembled nanostructures are known as quantum dashes and are typically formed during the molecular beam epitaxial growth on InP substrates. In this paper, we study properties of excitonic complexes confined in quantum dashes emitting in a broad spectral range from below 1.2 to 1.55 μm. We find peculiar trends for the biexciton and negative trion binding energies, with pronounced trion binding in smaller size quantum dashes. These experimental findings are then compared and qualitatively explained by atomistic theory. The theoretical analysis shows a fundamental role of correlation effects for the absolute values of excitonic binding energies. Eventually, we determine the bright exciton fine structure splitting (FSS), where both the experiment and theory predict a broad distribution of the splitting varying from below 50 to almost 180 μeV. We identify several key factors determining the FSS values in such nanostructures, including quantum dash size variation and composition fluctuations.

  5. 1300 nm wavelength InAs quantum dot photodetector grown on silicon.

    Science.gov (United States)

    Sandall, Ian; Ng, Jo Shien; David, John P R; Tan, Chee Hing; Wang, Ting; Liu, Huiyun

    2012-05-07

    The optical and electrical properties of InAs quantum dots epitaxially grown on a silicon substrate have been investigated to evaluate their potential as both photodiodes and avalanche photodiodes (APDs) operating at a wavelength of 1300 nm. A peak responsivity of 5 mA/W was observed at 1280 nm, with an absorption tail extending beyond 1300 nm, while the dark currents were two orders of magnitude lower than those reported for Ge on Si photodiodes. The diodes exhibited avalanche breakdown at 22 V reverse bias which is probably dominated by impact ionisation occurring in the GaAs and AlGaAs barrier layers. A red shift in the absorption peak of 61.2 meV was measured when the reverse bias was increased from 0 to 22 V, which we attributed to the quantum confined stark effect. This shift also leads to an increase in the responsivity at a fixed wavelength as the bias is increased, yielding a maximum increase in responsivity by a factor of 140 at the wavelength of 1365 nm, illustrating the potential for such a structure to be used as an optical modulator.

  6. Constructing a large-scale 3D Geologic Model for Analysis of the Non-Proliferation Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wagoner, J; Myers, S

    2008-04-09

    We have constructed a regional 3D geologic model of the southern Great Basin, in support of a seismic wave propagation investigation of the 1993 Nonproliferation Experiment (NPE) at the Nevada Test Site (NTS). The model is centered on the NPE and spans longitude -119.5{sup o} to -112.6{sup o} and latitude 34.5{sup o} to 39.8{sup o}; the depth ranges from the topographic surface to 150 km below sea level. The model includes the southern half of Nevada, as well as parts of eastern California, western Utah, and a portion of northwestern Arizona. The upper crust is constrained by both geologic and geophysical studies, while the lower crust and upper mantle are constrained by geophysical studies. The mapped upper crustal geologic units are Quaternary basin fill, Tertiary deposits, pre-Tertiary deposits, intrusive rocks of all ages, and calderas. The lower crust and upper mantle are parameterized with 5 layers, including the Moho. Detailed geologic data, including surface maps, borehole data, and geophysical surveys, were used to define the geology at the NTS. Digital geologic outcrop data were available for both Nevada and Arizona, whereas geologic maps for California and Utah were scanned and hand-digitized. Published gravity data (2km spacing) were used to determine the thickness of the Cenozoic deposits and thus estimate the depth of the basins. The free surface is based on a 10m lateral resolution DEM at the NTS and a 90m lateral resolution DEM elsewhere. Variations in crustal thickness are based on receiver function analysis and a framework compilation of reflection/refraction studies. We used Earthvision (Dynamic Graphics, Inc.) to integrate the geologic and geophysical information into a model of x,y,z,p nodes, where p is a unique integer index value representing the geologic unit. For seismic studies, the geologic units are mapped to specific seismic velocities. The gross geophysical structure of the crust and upper mantle is taken from regional surface

  7. The Global Diffusion of Societal Verification Tools: A Quantitative Assessment of the Public’s Ability to Engage Nonproliferation Treaty Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Sayre, Amanda M.; Kreyling, Sean J.; West, Curtis L.

    2015-07-11

    The spread of nuclear and dual-use technologies and the need for more robust, effective and efficient nonproliferation and arms control treaties has led to an increasing need for innovative verification approaches and technologies. This need, paired with advancements in online computing, mobile devices, commercially available satellite imagery and the evolution of online social networks, has led to a resurgence of the concept of societal verification for arms control and nonproliferation treaties. In the event a country accepts its citizens’ assistance in supporting transparency, confidence-building and societal verification, the host government will need a population that is willing and able to participate. While scholarly interest in societal verification continues to grow, social scientific research on the topic is lacking. The aim of this paper is to begin the process of understanding public societal verification capabilities, extend the availability of quantitative research on societal verification and set in motion complementary research to increase the breadth and depth of knowledge on this topic. This paper presents a potential framework and outlines a research roadmap for the development of such a societal verification capability index.

  8. Proceedings of the Symposium on the Non-Proliferation Experiment: Results and Implications for Test Ban Treaties, Rockville, Maryland, April 19-21, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Denny, Marvin D

    1994-01-01

    To address a critical verification issue for the current Non-Proliferation Treaty (NPT) and for a possible future Comprehensive Test Ban Treaty (CTBT), the Department of Energy sought to measure certain differences between an underground nuclear test and a chemical test in the same geology, so that other explosions could be identified. This was done in a field experiment code-named the NonProliferation Experiment (NPE).This comprehensive experiment was designed to determine the signatures of chemical explosions for a broad range of phenomena for comparison with those of previous nuclear tests. If significant differences can be measured, then these measures can be used to discriminate between the two types of explosions. In addition, when these differences are understood, large chemical explosions can be used to seismically calibrate regions to discriminate earthquakes from explosions. Toward this end, on-site and off-site measurements of transient phenomena were made, and on-site measurements of residual effects are in progress.Perhaps the most striking result was that the source function for the chemical explosion was identical to that of a nuclear one of about twice the yield. These proceedings provide more detailed results of the experiment.

  9. On the evolution of InAs thin films grown by molecular beam epitaxy on the GaAs(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Grabowski, Jan

    2010-12-14

    Semiconductor nanostructures are currently of high interest for a wide variety of electronic and optoelectronic applications. A large number of devices, in particular for the optical data transmission in the long-wavelength range, essential in modern communication, are based on InAs/GaAs quantum dot (QD) structures. Though the properties of the InAs/GaAs QDs have been extensively studied, only little is known about the formation and structure of the wetting layer (WL) yet. In the present work, the pathway of the InAs WL evolution is studied in detail. For this purpose, InAs thin films in the range of one monolayer (ML) are deposited on the GaAs(001) surface by molecular beam epitaxy (MBE) and studied by reflection high energy electron diffraction (RHEED) and in particular by scanning tunneling microscopy (STM). The InAs thin films are grown in both typical growth regimes, on the GaAs-c(4 x 4) and the GaAs-{beta}2(2 x 4) reconstructed surface, in a variety of thicknesses starting from submonolayers with 0.09 ML of InAs up to 1.65 ML of InAs exceeding the critical thickness for QD growth. In principle, three growth stages are found. At low InAs coverages, the indium adsorbs in agglomerations of typically eight In atoms at energetically preferable surface sites. In the STM images, the signatures of these In agglomerations appear with a clear bright contrast. A structural model for the initial formation of these signatures is presented, and its electronic and strain related properties are discussed. At an InAs coverage of about 0.67ML the initial surface transforms into a (4 x 3) reconstructed In{sub 2/3}Ga{sub 1/3}As ML and the detailed structure and strain properties of this surface are unraveled. On top of the InGaAs ML further deposited InAs forms a second layer, characterized by a typical zig-zag alignment of (2 x 4) reconstructed unit cells, with an alternating {alpha}2/{alpha}2-m configuration. In contrast to the previous surface reconstructions, where

  10. Seven law concepts on nuclear non-proliferation suggested by the International Group of Legal Experts (ILG)

    Energy Technology Data Exchange (ETDEWEB)

    Steen, G. [Djursholm (Sweden); Wredberg, L. [ILG Consultant LTD, Vienna (Austria)

    2001-03-01

    The ILG has worked as an independent group under the Swedish Support Programme on Nuclear Non-Proliferation in Central and Eastern Europe and Central Asia. The ILG's mission is concluded with this report. When developing the seven Law Concepts on national nuclear legislation that are presented in this report, the ILG has applied certain basic principles, which are firmly established in modern Western legislation. A summary of these principles is made here. They are essential cornerstones in laws and regulations that apply both to the nuclear industry and to other high technology areas, characterised by advanced safety and security requirements. Of essential importance is that the Operator alone is responsible for the fulfilment of requirements stipulated in laws and authority directives. The technical complexity of the nuclear industry and the far-reaching requirements on safety and security necessitate a qualified and complete national system of legislation and regulations. As all legislation in general, the nuclear legislation should be clear, easy to understand and give little room for misunderstandings and loopholes. It should also present the legally established requirements on safety and security in a form that facilitates the application and implementation by both state authorities, facility operators and individuals. The investigations of the causes of the Three Mile Island and Chernobyl accidents brought into focus the impact on nuclear safety from human failure. As a consequence, increased emphasis has since then been put on the development of an overall high safety culture in the nuclear field. It is recognised that a good safety culture also promotes the non-proliferation systems and safeguards measures and helps to reduce the risk of illicit trafficking. In a high safety culture environment, each individual facility employee has to be motivated and encouraged to carry out the assigned duties and responsibilities in accordance with rules and

  11. {sup 99m}Tc-MIBI/{sup 123}I-Na subtraction scanning for localized parathyroid adenoma in patients with asymptomatic/mild primary hyperparathyroidism

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Yuji; Funahashi, Hiroomi; Imai, Tsuneo [Nagoya Univ. (Japan). School of Medicine] [and others

    1996-09-01

    Primary hyperparathyroidism is most commonly detected as a mild elevation of the serum calcium concentration. In the present study, the utility of {sup 99m}Tc-methoxyisobutylisonitrile (MIBI) imaging before initial surgery was evaluated for localizing abnormal parathyroid glands in patients with asymptomatic and mild primary hyperparathyroidism. The results were compared with those of thallium-technetium subtraction scanning (TTSS). {sup 99m}Tc-MIBI/{sup 123}I-Na subtraction scanning was performed in 11 patients, and TTSS was performed in 10 of them. The sensitivity was 100% and the positive predictive value was 92% for {sup 99m}Tc-MIBI/{sup 123}I-Na, while the sensitivity was 50% and the positive predictive value was 100% for TTSS. The smallest gland detected weighed 85 mg in {sup 99m}Tc-MIBI/{sup 123}I-Na, and 570 mg in TTSS. There was a difference between the median weight of adenomas which were detected by {sup 99m}Tc-MIBI/{sup 123}I-Na (754 mg), and those which were detected by TTSS (1,195 mg). These results suggest that TTSS parathyroid scintigraphy could give way to {sup 99m}Tc-MIBI/{sup 123}I-Na parathyroid scintigraphy for improved detection of low-weight abnormal parathyroid glands. (author)

  12. Growth and electrical characterization of Zn-doped InAs and InAs{sub 1-x}Sb{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Venter, A., E-mail: andre.venter@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth (South Africa); Shamba, P.; Botha, L.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth (South Africa)

    2009-06-01

    The electrical properties of Zn doped InAs and InAsSb layers grown on semi-insulating GaAs by metal organic vapour phase epitaxy, using dimethyl zinc as the p-type dopant source, have been studied. The influence of dopant flow rate, V/III ratio and substrate orientation on the electrical properties of these InAs and InAs{sub 1-x}Sb{sub x} layers have been studied at a few appropriate growth temperatures. A promising group V source, tertiary butyl arsenic was used as an alternative to arsenic hydride in the case of InAs growth. The electrical properties of the InAs and InAs{sub 1-x}Sb{sub x} epitaxial layers were mainly studied by the Hall effect. However, surface accumulation in these materials results in deceptive Hall results being extracted. A two layer model (assuming the layer to consist of two parallel conducting paths viz. surface and bulk) has therefore been used to extract sensible transport properties. In addition, conventional Hall measurements ignores the high electron to hole mobility ratio in InAs and InAsSb leading to erroneous transport properties.

  13. Strategic planning of INA-CORS development for public service and tectonic deformation study

    Science.gov (United States)

    Syetiawan, Agung; Gaol, Yustisi Ardhitasari Lumban; Safi'i, Ayu Nur

    2017-07-01

    GPS technology can be applied for surveying, mapping and research purposes. The simplicity of GPS technology for positioning make it become the first choice for survey compared with another positioning method. GPS can measure a position with various accuracy level based on the measurement method. In order to facilitate the GPS positioning, many organizations are establishing permanent GPS station. National Geodetic Survey (NGS) called it as Continuously Operating Reference Stations (CORS). Those devices continuously collect and record GPS data to be used by users. CORS has been built by several government agencies for particular purposes and scattered throughout Indonesia. Geospatial Information Agency (BIG) as a geospatial information providers begin to compile a grand design of Indonesia CORS (INA-CORS) that can be used for public service such as Real Time Kinematic (RTK), RINEX data request, or post-processing service and for tectonic deformation study to determine the deformation models of Indonesia and to evaluate the national geospatial reference system. This study aims to review the ideal location to develop CORS network distribution. The method was used is to perform spatial analysis on the data distribution of BIG and BPN CORS overlayed with Seismotectonic Map of Indonesia and land cover. The ideal condition to be achieved is that CORS will be available on each radius of 50 km. The result showed that CORS distribution in Java and Nusa Tenggara are already tight while on Sumatra, Celebes and Moluccas are still need to be more tighten. Meanwhile, the development of CORS in Papua will encounter obstacles toward road access and networking. This analysis result can be used as consideration for determining the priorities of CORS development in Indonesia.

  14. Multilateral Cooperation on Nonproliferation

    Science.gov (United States)

    2012-10-01

    denuclearization , see Jeffrey W. Knopf, “The Importance of International Learning,” Review of International Studies 29, no. 2 (April 2003), 187-209...weapons or the denuclearization of Ukraine, Kazakhstan, and Belarus. She noted that, in contrast to other cases that are multilateral, CTR was...confidence that they could effectively verify mutual denuclearization . ABACC was not sufficient to persuade the rest of the international community about

  15. The Nonproliferation Review

    Energy Technology Data Exchange (ETDEWEB)

    RAJEN,GAURAV; BIRINGER,KENT L.

    2000-07-28

    The aim of this paper is to understand the numerous nuclear-related agreements that involve India and Pakistan, and in so doing identify starting points for future confidence-creating and confidence-building projects. Existing nuclear-related agreements provide a framework under which various projects can be proposed that foster greater nuclear transparency and cooperation in South Asia. The basic assumptions and arguments underlying this paper can be summarized as follows: (1) Increased nuclear transparency between India and Pakistan is a worthwhile objective, as it will lead to the irreversibility of extant nuclear agreements, the prospects of future agreements; and the balance of opacity and transparency required for stability in times of crises; (2) Given the current state of Indian and Pakistani relations, incremental progress in increased nuclear transparency is the most likely future outcome; and (3) Incremental progress can be achieved by enhancing the information exchange required by existing nuclear-related agreements.

  16. Demonstration of Quantum Entanglement between a Single Electron Spin Confined to an InAs Quantum Dot and a Photon

    Science.gov (United States)

    2013-04-16

    AUTHOR(S) J. Schaibley, A. Burgers, G. McCracken , L. Duan, P. Berman, D. Steel, A. Bracker, D. Gammon, and I. Sham 5d. PROJECT NUMBER QEST 5e...TERMS quantum entanglement, electron spin, photon, quantum dot, laser J. R. Schaibley, A. P. Burgers, G. A. McCracken , L.-M. Duan, P. R. Berman, D...Single Electron Spin Confined to an InAs Quantum Dot and a Photon J. R. Schaibley, A. P. Burgers, G.A. McCracken , L.-M. Duan, P. R. Berman, and D.G

  17. Detection of single magnetic bead for biological applications using an InAs quantum-well micro-Hall sensor

    Science.gov (United States)

    Mihajlović, Goran; Xiong, Peng; von Molnár, Stephan; Ohtani, Keita; Ohno, Hideo; Field, Mark; Sullivan, Gerard J.

    2005-09-01

    Room-temperature detection of a single commercial superparamagnetic bead (1.2μm in diameter) suitable for biological applications has been realized using an InAs quantum-well micro-Hall sensor. The detection was demonstrated using phase-sensitive detection on a single Hall cross as well as in a Hall gradiometry setup. The high signal to noise ratio, obtained in both configurations, promises detection of single nanometer-size particles by further miniaturization of the device to submicron dimensions.

  18. Cr-Doped InAs Self-Organized Diluted Magnetic Quantum Dots with Room-Temperature Ferromagnetism

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yu-Hong; ZHAO Jian-Hua; BI Jing-Feng; WANG Wei-Zhu; JI Yang; WU Xiao-Guang; XIA Jian-Bai

    2007-01-01

    Cr-doped InAs self-organized diluted magnetic quantum dots (QDs) are grown by low-temperature molecularbeam epitaxy. Magnetic measurements reveal that the Curie temperature of all the InAs:Cr QDs layers with Cr/In flux ratio changing from 0.026 to 0.18 is beyond 400K. High-resolution cross sectional transmission electron microscopy images indicate that InAs:Cr QDs are of the zincblende structure. Possible origins responsible for the high Curie temperature are discussed.

  19. Size dependence of the wavefunction of self-assembled InAs quantum dots from time-resolved optical measurements

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Stobbe, Søren; Nikolaev, Ivan S.;

    2008-01-01

    and a theoretical model, we determine the striking dependence of the overlap of the electron and hole wavefunctions on the quantum dot size. We conclude that the optical quality is best for large quantum dots, which is important in order to optimally tailor quantum dot emitters for, e.g., quantum electrodynamics......The radiative and nonradiative decay rates of InAs quantum dots are measured by controlling the local density of optical states near an interface. From time-resolved measurements, we extract the oscillator strength and the quantum efficiency and their dependence on emission energy. From our results...

  20. Wideband luminescence of high-density InAs quantum dots on GaAsSb/GaAs layers

    Science.gov (United States)

    Osaka, Yuji; Tanabe, Hiroyuki; Yamada, Kazuhiro; Yamaguchi, Koichi

    2013-09-01

    In order to achieve wideband luminescence, ultrahigh density InAs quantum dots (QDs) were grown on GaAsSb buffer layers by molecular beam epitaxy under various growth conditions. Ultrahigh density of 3.8-5.2×1011 cm-2 and large size fluctuation were obtained. Photoluminescence (PL) spectra of ultrahigh density QD layers were changed by adjusting the growth conditions. Three ultrahigh density QD layers with different PL spectra were stacked on GaAs (001) substrate. The PL spectrum of edge emission revealed strong intensity and a broad linewidth of 194 nm. The presented QD structures are expected for development of wideband superluminescent diodes.

  1. Utjecaj značajki domaćina na progresiju jetrene fibroze kod kroničnog hepatitisa C

    OpenAIRE

    Gregurević, I.; Vince, A; Kurelac, I

    2006-01-01

    Smatra se da oko 200 milijuna ljudi u svijetu boluje od kroničnog hepatitisa C što predstavlja velik javnozdravstveni problem. Kronični hepatitis C je bolest vrlo heterogenog kliničkog tijeka pri čemu je osnovni čimbenik dugoročne prognoze brzina napredovanja jetrene fibroze koja konačno rezultira cirozom i njenim komplikacijama uključivo i nastankom hepatocelularnog karcinoma. Na prirodni tijek bolesti značajno utječu karakteristike domaćina. S lošijom prognozom povezuju se muški spol, stari...

  2. Ultrafast dynamics in InAs quantum dot and GaInNAs quantum well semiconductor heterostructures

    OpenAIRE

    Malins, David B

    2007-01-01

    The quantum confined Stark effect (QCSE) and ultrafast absorption dynamics near the bandedge have been investigated in p-i-n waveguides comprising quantum confined heterostructures grown on GaAs substrates, for emission at 1.3um. The materials are; isolated InAs/InGaAs dot-in-a-well (DWELL) quantum dots (QD), bilayer InAs quantum dots and GaInNAs multiple quantum wells (MQW). The focus was to investigate these dynamics in a planar waveguide geometry, for the purpose of large scale integ...

  3. Literaturgeschichte anders gelesen. Ina Schaberts Englische Literaturgeschichte des 20. Jahrhunderts als Kosmos männlicher und weiblicher Stimmen

    Directory of Open Access Journals (Sweden)

    Ingrid Hotz-Davies

    2007-03-01

    Full Text Available Ina Schaberts Abhandlung zur Britischen Literatur des zwanzigsten Jahrhunderts ist eine Literaturgeschichte der etwas anderen Art: die Literatur wird gesehen als ein Kosmos, der von männlichen und weiblichen Autoren bevölkert ist, die sich in einer ständigen Unterhaltung miteinander befinden, die mal freundlich, mal feindselig ausfallen mag, die aber als Unterhaltung die Literatur einer Epoche bestimmt. Schabert zeichnet eine detaillierte und faszinierende Abfolge dieser Interaktionen, die vom klassischen Modernismus über verschiedene politische ‚Realismen‘ zur postmodernen Welt der Diversifizierung der Ethnien und Geschlechteroptionen führt.

  4. O genocídio de Ruanda e a dinâmica da inação estadunidense

    OpenAIRE

    Araujo, Cintia Ribeiro de [UNESP

    2012-01-01

    O presente trabalho tem como objetivo avaliar os motivos que impediram a intervenção dos Estados Unidos no Genocídio de Ruanda, em 1994. A inação da comunidade internacional diante do conflito gerou grande constrangimento e profundos debates acerca da seletividade nas questões de intervenção humanitária. A proposta da pesquisa é discutir como a partilha da África interferiu nas relações da população de Ruanda durante o período colonial, que acabou por culminar no conflito de 1994 e, posterior...

  5. Lateral interdot carrier transfer in an InAs quantum dot cluster grown on a pyramidal GaAs surface.

    Science.gov (United States)

    Liang, B L; Wong, P S; Pavarelli, N; Tatebayashi, J; Ochalski, T J; Huyet, G; Huffaker, D L

    2011-02-04

    InAs quantum dot clusters (QDCs), which consist of three closely spaced QDs, are formed on nano-facets of GaAs pyramidal structures by selective-area growth using metal-organic chemical vapor deposition. Photoluminescence (PL) and time-resolved PL (TRPL) experiments, measured in the PL linewidth, peak energy and QD emission dynamics indicate lateral carrier transfer within QDCs with an interdot carrier tunneling time of 910 ps under low excitation conditions. This study demonstrates the controlled formation of laterally coupled QDCs, providing a new approach to fabricate patterned QD molecules for optical computing applications.

  6. Volmer–Weber InAs quantum dot formation on InP (113)B substrates under the surfactant effect of Sb

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yu, E-mail: yu.zhao@insa-rennes.fr; Bertru, Nicolas; Folliot, Hervé; Rohel, Tony [Université Européenne de Bretagne, INSA, FOTON, UMR-CNRS 6082, 20 Avenue des Buttes de Coësmes, F-35708 Rennes Cedex 7 (France); Mauger, Samuel J. C.; Koenraad, Paul M. [COBRA Inter-University Research Institute, Eindhoven University of Technology, P.O. Box 513, NL-5600MB Eindhoven (Netherlands)

    2014-07-21

    We report on Sb surfactant growth of InAs nanostructures on GaAs{sub 0.51}Sb{sub 0.49} layers deposited on InP (001) and on (113)B oriented substrates. On the (001) orientation, the presence of Sb significantly favors the two-dimensional growth regime. Even after the deposition of 5 mono-layers of InAs, the epitaxial film remains flat and InAs/GaAs{sub 0.51}Sb{sub 0.49} type-II quantum wells are achieved. On (113)B substrates, same growth runs resulted in formation of high density InAs islands. Microscopic studies show that wetting layer is missing on (113)B substrates, and thus, a Volmer-Weber growth mode is concluded. These different behaviors are attributed to the surface energy changes induced by Sb atoms on surface.

  7. Dependence of bimodal size distribution on temperature and optical properties of InAs quantum dots grown on vicinal GaAs (100) substrates by using MOCVD

    Institute of Scientific and Technical Information of China (English)

    Liang Song; Zhu Hong-Liang; Pan Jiao-Qing; Wang Wei

    2006-01-01

    Self-assembled InAs quantum dots (QDs) are grown on vicinal GaAs (100) substrates by using metal-organic chemical vapour deposition (MOCVD). An abnormal temperature dependence of bimodal size distribution of InAs quantum dots is found. As the temperature increases, the density of the small dots grows larger while the density of the large dots turns smaller, which is contrary to the evolution of QDs on exact GaAs (100) substrates. This trend is explained by taking into account the presence of multiatomic steps on the substrates. The optical properties of InAs QDs on vicinal GaAs(100) substrates are also studied by photoluminescence (PL) . It is found that dots on a vicinal substrate have a longer emission wavelength, a narrower PL line width and a much larger PL intensity.

  8. Effects of Low Temperature Stress and INA Bacteria on Chlorophyll a Fluorescence Induction Kinetics in Young Fruit of Two Apricot Cultivars

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-min; MENG Qing-rui; PENG Wei-xiu; WANG Xue-dong; ZHANG Yuan-hui; SUN Fu-zai; ZHAO Ting-chang; LI Shao-hua

    2002-01-01

    Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence inyoung fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity(Fv/Fo) ,conversion efficiency of primary light energy (Fv/Fm)of PS Ⅱ and photochemical quenching (qP) inyoung fruit of two apricot cultivars. Low temperature enhanced non-photochemical quenching qN, decreasingthe quantum yield of photosynthetic electron transfer. The presence of ice nucleating active (INA) bacteria in-tensified the effects of low temperature, raised the injury temperature threshold from - 4℃ to - 2 - - 3℃.INA bacteria can be a factor to induce frost susceptibility of apricot fruit. The amount of damaged PS Ⅱ activi-ty center was related to apricot fruit size and cultivar.

  9. Synthesis, crystal structure and EPR studies of vanadyl doped [Co(2-nbH)2(ina)2(H2O)] complex

    Science.gov (United States)

    Bozkurt, Esat; Çelik, Yunus; Çöpür, Fatma; Dege, Necmi; Topcu, Yıldıray; Karabulut, Bünyamin

    2016-08-01

    A novel aquabis(isonicotinamide-κN1)bis(2-nitrobenzoato-κ2O,O‧;κO)cobalt(II), (hereafter [Co(2-nbH)2(ina)2(H2O)]; 2-nbH: 2-nitrobenzoic acid; ina: isonicotinamide), complex was synthesized and characterized by using various techniques. The crystal structure was determined by X-ray diffraction (XRD) method. The magnetic properties of VO2+ doped [Co(2-nbH)2(ina)2(H2O)] complex were obtained by electron paramagnetic resonance (EPR) technique. The angular variation of EPR spectra shows that two different VO2+ complexes are present in the lattice. The FT-IR spectra of this compound were discussed in relation to other compounds containing 2-nitrobenzoato or isonicotinamide ligands. Thermal stability and reactivity of this complex were also studied by thermal analysis methods (TG/DTG/DTA).

  10. Balancing Acts

    Science.gov (United States)

    ... Past Issues Special Section: Focus on Communication Balancing Acts Past Issues / Fall 2008 Table of Contents For ... scientific research on hearing, balance, smell, taste, voice, speech, and language—common elements in how we perceive ...

  11. Tight-binding approach to excitons bound to monolayer impurity planes: strong radiative properties of InAs in GaAs

    OpenAIRE

    Iotti, Rita Claudia

    1998-01-01

    A theory of Wannier-Mott excitons bound to monolayer (ML) impurity planes in semiconductors, which is based on Green's function tight-binding calculations of the single-particle states, is presented. Binding energies and oscillator strengths for one and two MLs of InAs in GaAs are predicted to be much larger than in the usual InxGa1-xAs/GaAs thick quantum wells. The reason is the increase of effective mass of both carriers due to folding of the InAs bands along the growth direction. The resul...

  12. Intrinsic quantum dots in InAs nanowires; Intrinsische Quantenpunkte in InAs-Nanodraehten

    Energy Technology Data Exchange (ETDEWEB)

    Weis, Karl Martin Darius

    2013-07-22

    This work deals with InAs nanowire field effect transistors in back gate configuration. In such devices, quantum dots can form at low temperatures in the order of magnitude of a few Kelvin. These dots are henceforth referred to as intrinsic as they are not intentionally defined by electrodes. For the interpretation of their stability diagrams, a thorough knowledge of the structure and transport properties of the nanowires is required. Therefore, first of all, the influence of growth method and doping on the transport properties is studied at room temperature. The wires are grown by two types of metal-organic vapour phase epitaxy: a selective-area (SA-MOVPE) and an Au-catalyzed vapour-liquid-solid method (VLS-MOVPE). Transport data shows that the background doping of VLS-MOVPE wires is higher than for SA-MOVPE wires, but the variability of the transport properties is lower. The polytypism of the SA-MOVPE wires (they are composed of wurtzite and zinc blende segments) is a possible explanation for the second observation. Furthermore, it is shown that the measured transport properties significantly depend on the dielectric environment of the nanowires and on the way the electrical measurements are done (two- or four-terminal configuration). The conductivity is tunable via doping and the gate voltage. Conductivity measurements in the temperature range from 10 K to 300 K show that different transport regimes can occur (partially metallic behaviour for sufficiently high conductivity, otherwise purely semiconducting behaviour). This is attributed to different positions of the Fermi level and thus, a different effect of potential fluctuations. If conductivity and temperature are sufficiently low, the onset of Coulomb blockade is observed for semiconducting samples. It is even possible to tune the very same sample to different regimes via the gate voltage. The semiconducting behaviour observed in many samples contradicts the Thomas-Fermi theory. This is attributed to the

  13. MATLAB implementation of a dynamic clamp with bandwidth >125 KHz capable of generating INa at 37°C

    Science.gov (United States)

    Clausen, Chris; Valiunas, Virginijus; Brink, Peter R.; Cohen, Ira S.

    2012-01-01

    We describe the construction of a dynamic clamp with bandwidth >125 KHz that utilizes a high performance, yet low cost, standard home/office PC interfaced with a high-speed (16 bit) data acquisition module. High bandwidth is achieved by exploiting recently available software advances (code-generation technology, optimized real-time kernel). Dynamic-clamp programs are constructed using Simulink, a visual programming language. Blocks for computation of membrane currents are written in the high-level matlab language; no programming in C is required. The instrument can be used in single- or dual-cell configurations, with the capability to modify programs while experiments are in progress. We describe an algorithm for computing the fast transient Na+ current (INa) in real time, and test its accuracy and stability using rate constants appropriate for 37°C. We then construct a program capable of supplying three currents to a cell preparation: INa, the hyperpolarizing-activated inward pacemaker current (If), and an inward-rectifier K+ current (IK1). The program corrects for the IR drop due to electrode current flow, and also records all voltages and currents. We tested this program on dual patch-clamped HEK293 cells where the dynamic clamp controls a current-clamp amplifier and a voltage-clamp amplifier controls membrane potential, and current-clamped HEK293 cells where the dynamic clamp produces spontaneous pacing behavior exhibiting Na+ spikes in otherwise passive cells. PMID:23224681

  14. Topological Phases in InAs1 -xSbx: From Novel Topological Semimetal to Majorana Wire

    Science.gov (United States)

    Winkler, Georg W.; Wu, QuanSheng; Troyer, Matthias; Krogstrup, Peter; Soluyanov, Alexey A.

    2016-08-01

    Superconductor proximitized one-dimensional semiconductor nanowires with strong spin-orbit interaction (SOI) are, at this time, the most promising candidates for the realization of topological quantum information processing. In current experiments the SOI originates predominantly from extrinsic fields, induced by finite size effects and applied gate voltages. The dependence of the topological transition in these devices on microscopic details makes scaling to a large number of devices difficult unless a material with dominant intrinsic bulk SOI is used. Here, we show that wires made of certain ordered alloys InAs1 -xSbx have spin splittings up to 20 times larger than those reached in pristine InSb wires. In particular, we show this for a stable ordered CuPt structure at x =0.5 , which has an inverted band ordering and realizes a novel type of a topological semimetal with triple degeneracy points in the bulk spectrum that produce topological surface Fermi arcs. Experimentally achievable strains can either drive this compound into a topological insulator phase or restore the normal band ordering, making the CuPt-ordered InAs0.5Sb0.5 a semiconductor with a large intrinsic linear in k bulk spin splitting.

  15. Carrier dynamics of strain-engineered InAs quantum dots with (In)GaAs surrounding material

    Science.gov (United States)

    Nasr, O.; Chauvin, N.; Alouane, M. H. Hadj; Maaref, H.; Bru-Chevallier, C.; Sfaxi, L.; Ilahi, B.

    2017-02-01

    The present study reports on the optical properties of epitaxially grown InAs quantum dots (QDs) inserted within an InGaAs strain-reducing layer (SRL). The critical energy states in such QD structures have been identified by combining photoluminescence (PL) and photoluminescence of excitation (PLE) measurements. Carrier lifetime is investigated by time-resolved photoluminescence (TRPL), allowing us to study the impact of the composition of the surrounding materials on the QD decay time. Results showed that covering the InAs QDs with, or embedding them within, an InGaAs SRL increases the carrier dynamics, while a shorter carrier lifetime has been observed when they are grown on top of an InGaAs SRL. Investigation of the dependence of carrier lifetime on temperature showed good stability of the decay time, deduced from the consequences of improved QD confinement. The findings suggest that embedding or capping the QDs with SRL exerts optimization of their room temperature optical properties.

  16. Performance investigation of InAs based dual electrode tunnel FET on the analog/RF platform

    Science.gov (United States)

    Anand, Sunny; Sarin, R. K.

    2016-09-01

    In this paper for the first time, InAs based doping-less Tunnel FET is proposed and investigated. This paper also demonstrates and discusses the impact of gate stacking (SiO2 + HfO2) with equivalent oxide thickness EOT = 0.8 for analog/RF performance. The charge plasma technique is used to form source/drain region on an intrinsic InAs body by selecting proper work function of metal electrode. The paper compares different combinations of gate stacking (SiO2 and HfO2) on the basis of different analog and RF parameters such as transconductance (gm), transconductance to drive current ratio (gm/ID), output conductance (gd), intrinsic gain (AV), total gate capacitance (Cgg) and unity-gain cutoff frequency (fT). The proposed device produces an ON state current of ION ∼6 mA along with ION/IOFF ∼1012, point subthreshold slope (SS ∼ 1.9 mV/dec), average subthreshold slope (AV-SS ∼ 14.2 mV/dec) and cut-off frequency in Terahertz. The focus of this work is to eliminate the fabrication issues and providing the enhanced performance compared to doped device.

  17. Effects of annealing on self-assembled InAs quantum dots and wetting layer in GaAs matrix

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, J.; Babinski, A.; Bozek, R.; Szepielow, A.; Baranowski, J.M.

    2001-04-18

    Post-growth thermal annealing effects on InAs/GaAs quantum dots (QDs) near Stransky-Krastanow transformation were investigated. Self-assembled QDs of average size of about 10 nm were grown by metal organic vapour phase epitaxy. The photoluminescence (PL) due to emission from QDs as well as two peaks due to emission from the strained InAs wetting layer (WL) were observed in as-grown samples. Bimodal structure of the WL PL was attributed to WL regions of different thickness. There was almost no difference in the PL spectrum after 30 s annealing at 600 C. However, annealing at temperatures in the range between 700 C and 950 C resulted in quenching of the PL from QDs and the thinner WL. The PL peak from the new, thicker WL blue-shifted and narrowed with increasing annealing temperature. This behavior was in agreement with TEM observations. Complete dissolution of the QDs and substantial broadening of the WL was observed. All our results indicate that thermally induced modifications of the WL rather than QDs can be responsible for the blue-shift and narrowing of the PL peaks in structures containing InAs QDs.

  18. Effects of annealing on self-assembled InAs quantum dots and wetting layer in GaAs matrix

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, J.; Babinski, A.; Bozek, R.; Szepielow, A.; Baranowski, J.M.

    2001-04-18

    Post-growth thermal annealing effects on InAs/GaAs quantum dots (QDs) near Stransky-Krastanow transformation were investigated. Self-assembled QDs of average size of about 10 nm were grown by metal-organic vapor phase epitaxy. The photoluminescence (PL) due to emission from QDs as well as two peaks due to emission from the strained InAs wetting layer (WL) were observed in as-grown samples. Bimodal structure of the WL PL was attributed to WL regions of different thickness. There was almost no difference in the PL spectrum after 30 s annealing at 600 C. However, annealing at temperatures in the range between 700 C and 950 C resulted in quenching of the PL from QDs and the thinner WL. The PL peak from the new, thicker WL blue-shifted and narrowed with increasing annealing temperature. This behavior was in agreement with TEM observations. Complete dissolution of the QDs and substantial broadening of the WL was observed. All our results indicate that thermally induced modifications of the WL rather than QDs can be responsible for the blue-shift and narrowing of the PL peaks in structures containing InAs QDs.

  19. Optical and structural properties of InAs nanoclusters in crystalline Si obtained through sequential ion implantation and RTA

    Energy Technology Data Exchange (ETDEWEB)

    Sortica, Mauricio A.; Canut, Bruno; Chauvin, Nicolas [Institut des Nanotechnologies de Lyon INL-UMR5270, INSA - Lyon, CNRS, 7 av. Jean Capelle, 69621, Villeurbanne (France); Hatori, Masahiro; Dias, Johnny F. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul IF-UFRGS, av. Bento Goncalves 9500, 91501-970, Porto Alegre - RS (Brazil); Marty, Olivier [Institut des Nanotechnologies de Lyon INL-UMR5270, Universite Claude Bernard Lyon 1, 8 rue Andre-Marie Ampere, 69622, Villeurbanne (France)

    2015-12-15

    Si (100) wafers were implanted at 500 C with 250 keV As ions and 350 keV In ions in this order. The implantations were carried out with three different fluences, namely 1 x 10{sup 16}, 2 x 10{sup 16}, and 5 x 10{sup 16} cm{sup -2}. The samples were annealed with rapid thermal annealing (RTA) for 30 s at temperatures ranging from 800 up to 1000 C. Different techniques like photoluminescence (PL) and Rutherford backscattering spectrometry (RBS) were employed to characterize the samples. Finally, scanning and transmission electron microscopy (SEM and TEM, respectively) provided further structural information of the InAs nanoclusters. The results indicate that InAs nanoprecipitates are formed after RTA treatment. Moreover, a broad photoluminescence peak was observed in all samples submitted to RTA. RBS results reveal that losses of implanted ions due to diffusion processes can be minimized through the use of RTA, depending of the fluence of ion implantation. Finally, the present results suggest that the photoluminescence yield depends on the degree of the radiation damage induced in the Si matrix during the implantation process. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Optical anisotropy in self-assembled InAs nanostructures grown on GaAs high index substrate.

    Science.gov (United States)

    Bennour, M; Saidi, F; Bouzaïene, L; Sfaxi, L; Maaref, H

    2012-01-15

    We present a study of the optical properties of InAs self-assembled nanostructures grown by molecular beam epitaxy on GaAs(11N)A substrates (N = 3-5). Photoluminescence (PL) measurements revealed good optical properties of InAs quantum dots (QDs) grown on GaAs(115)A compared to those grown on GaAs(113)A and (114)A orientations substrate. An additional peak localized at 1.39 eV has been shown on PL spectra of both GaAs(114)A and (113)A samples. This peak persists even at lower power density. Supporting on the polarized photoluminescence characterization, we have attributed this additional peak to the quantum strings (QSTs) emission. A theoretical study based on the resolution of the three dimensional Schrödinger equation, using the finite element method, including strain and piezoelectric-field effect was adopted to distinguish the observed photoluminescence emission peaks. The mechanism of QDs and QSTs formation on such a high index GaAs substrates was explained in terms of piezoelectric driven atoms and the equilibrium surfaces at edges.

  1. Sünnitage armastus! / Birgit Haan, Jaana Mihailišina, Maarja Kukumägi ; küsitlenud Triin Tähnas

    Index Scriptorium Estoniae

    Haan, Birgit

    2007-01-01

    Intervjuu Tarvastu Gümnaasiumi näiteringi tüdrukute Birgit Haani, Jaana Mihailišina ja Maarja Kukumägiga etendusest "Sünnitage armastus", millega nad võitsid õpilaskonverentsi "Armastuse terviseks" raames toimunud teatrifestivalil esikoha

  2. Gate Stack Engineering and Thermal Treatment on Electrical and Interfacial Properties of Ti/Pt/HfO2/InAs pMOS Capacitors

    Directory of Open Access Journals (Sweden)

    Chung-Yen Chien

    2012-01-01

    Full Text Available Effects of gate stack engineering and thermal treatment on electrical and interfacial properties of Ti/Pt/HfO2/InAs metal insulator semiconductor (MIS capacitors were systematically evaluated in terms of transmission electron microscopy, energy dispersive X-ray spectroscopy, current-voltage, and capacitance-voltage characterizations. A 10 nm thick Pt metal effectively suppresses the formation of interfacial oxide, TiO2, between the Ti gate and HfO2 gate dielectric layer, enhancing the gate modulation on the surface potential of InAs. An in situ HfO2 deposition onto the n-InAs channel with an interfacial layer (IL of one-monolayer InP followed by a 300°C post-metal-anneal produces a high-quality HfO2/InAs interface and thus unravels the annoying Fermi-level pinning, which is evidenced by the distinct capacitance dips in the high-/low-frequency C-V characteristics. The interface trap states could be further suppressed by replacing the InP IL by an As-rich InAs, which is substantiated by a gate leakage reduction and a steep voltage-dependent depletion capacitance.

  3. Growth direction control of InAs nanowires on (0 0 1) Si substrate with SiO2/Si nano-trench

    Science.gov (United States)

    Chen, Wei-Chieh; Chen, Li-Hsing; Lin, Yen-Ting; Lin, Hao-Hsiung

    2017-04-01

    We report on direction control of InAs nanowire (NW) grown on (0 0 1) Si substrate with SiO2/Si nanotrench. A two-step method was used to enhance the direction control. In the first step, we aligned the In beam with the longitudinal axis of the trench utilizing shadowing effect to nucleate InAs on only one trench end. In the second step, the growth proceeded with substrate rotation. Comparing with NW growths using only one step, either the first one or the second one, two-step growth demonstrates highly directional NWs. Transmission electron microscope (TEM) and one dimensional Fourier image analyses show that InAs NW can be easily grown from the (1 bar 1 1) Si residue, which was left at trench ends by fabrication process, due to the tiny residue volume and low V/III ratio. In contrast, InAs nucleus, located at the center of the trench, developed into island and cluster because of the high V/III ratio and large lattice mismatch.

  4. Tuismitheoirí ina ngníomhairí in earnáil an Ghaeloideachais

    Directory of Open Access Journals (Sweden)

    Gabrielle Nig Uidhir

    2016-10-01

    Full Text Available Le dhá scór bliain anuas, is tuismitheoirí a chruthaigh an t-éileamh ar an oideachas lán-Ghaeilge agus a thiomáin borradh na scoileanna. Mar sin de, is fiú go mór aird an taighdeora a dhíriú ar na fachtóirí a spreagann an Ghaelscolaíocht mar rogha acu agus ar na tosca a mheallann a rannpháirtíocht nó a chuireann ina haghaidh. Sa mhórstaidéar as a n-eascraíonn an aiste taighde seo, tá rannpháirtíocht tuismitheoirí in oideachas lán-Ghaeilge a gcuid páistí ar na ceisteanna a ndearnadh anailís orthu. Cé gur peirspictíocht na múnlaí difriúla soláthair atá lárnach sa mhórstaidéar (Ó Duibhir et al. 2015, dírítear aird ar cheisteanna a bhaineann le tuismitheoirí san earnáil lán-Ghaeilge go speisialta san aiste seo. Go ginearálta, léirigh tuismitheoirí sásamh leis an oideachas a fuair a gcuid páistí agus bhí dearcadh dearfach le sonrú i leith na tacaíochta a chuirtear ar fáil dóibh. Tá an baol ann nach dtuigtear go forleathan impleachtaí a bhaineann le rannpháirtíocht tuismitheoirí agus an nasc le dearcadh na ndaltaí ar an fhoghlaim. Sa taighde seo, mar shampla, fuarthas gaol idir patrúin teanga sa bhaile agus an tuairim a bhí ag daltaí ar an spreagadh a thug nó nár thug tuismitheoirí dóibh. Nuair a labhair tuismitheoirí Béarla amháin sa bhaile lena bpáistí, thuairiscigh na daltaí scóir ní b’ísle maidir le spreagadh ó thuismitheoirí agus maidir le féinchoincheap ó thaobh a gcumais sa Ghaeilge de. De réir a chéile, tá an corpas taighde ar ghnéithe den oideachas lán-Ghaeilge ag dul i méid agus ag soláthar fianaise a threoraíonn pleanáil agus dul chun cinn an tsoláthair. Is éard is mian le húdair an ailt seo ná cur leis an tuiscint atá ar fáil ar an ról a imríonn tuismitheoirí i scolaíocht lán-Ghaeilge a gcuid páistí, léargas a thabhairt ar roinnt castachtaí sa phróiseas agus ar dhea-chleachtas a threisíonn rannpháirtíocht tuismitheoirí.

  5. Stress evolution during growth of InAs on GaAs measured by an in-situ cantilever beam setup

    Energy Technology Data Exchange (ETDEWEB)

    Hu Dongzhi

    2007-02-13

    The influence of stress on the growth of InAs on GaAs(001) by molecular beam epitaxy (MBE) is investigated in this thesis. Film force curves were measured for InAs deposition under As-rich as well as In-rich growth conditions. The growth under As-rich conditions proceeds in the Stranski- Krastanov growth mode, meaning that quantum dots are formed after the initial growth of a wetting layer. During subsequent growth interruptions or intentional annealing at the growth temperature, the quantum dots undergo ripening. This growth mode of InAs films and the subsequent annealing behavior were studied in detail in this thesis. To understand the influence of strain on the growth mechanisms, the film force curves were analyzed and correlated to the morphological evolution of the InAs films during deposition and especially during annealing. Models were developed to fit and explain the relaxation of the film force measured during the annealing of InAs quantum dots. At temperatures lower than 470 C, quantum dots undergo standard Ostwald ripening. Different mechanisms, such as kinetic and diffusion limited, determine the ripening process. Fits of models based on these mechanisms to the film force relaxation curves, show, that although the relaxation curve for annealing at 440 C can be fitted reasonably well with all the models, the model describing ripening limited by the diffusion along dot boundaries yields a slightly better fit. The relaxation curves obtained at 455 C and 470 C can be fitted very well only with the model in which the ripening is controlled by the attachment/detachment of atoms on the dot surface. Annealing of quantum dots at temperatures higher than 500 C shows a very different behavior. Atomic force microscopy images reveal that the quantum dots ripen first and then dissolve after 450 s-600 s annealing. (orig.)

  6. BIAYA KLAIM INA CBGS DAN BIAYA RIIL PENYAKIT KATASTROPIK RAWAT INAP PESERTA JAMKESMAS DI RUMAH SAKIT STUDI DI 10 RUMAH SAKIT MILIK KEMENTERIAN KESEHATAN JANUARI–MARET 2012

    Directory of Open Access Journals (Sweden)

    Wasis Budiarto

    2013-08-01

    Full Text Available Latar belakang: Implementasi sistem INA-CBGs bagi pasien penyakit katastropik (jantung, kanker, stroke peserta Jamkesmas di rumah sakit, memberikan konsekuensi di satu pihak bahwa penyakit katastropik merupakan ancaman terhadap membengkaknya pembiayaan Jamkesmas di masa datang, sedangkan di pihak lain, rumah sakit merasakan bahwa biaya penggantian klaim INA CBGs lebih rendah dari tarif yang berlaku dirumah sakit. Tujuan: Tujuan penelitian ini untuk memperoleh gambaran biaya pengobatan penyakit katastropik dan perbandingan pembiayaan klaim berdasarkan INA-DRGs dengan biaya pengobatan riil penyakit katastropik dirumah sakit. Jenis penelitian adalah deskriptif menurut perspektif rumah sakit. Metode: Metode pengambilan data dilakukan secara retrospektif yang diambil dari penelusuran dokumen catatan medik pasien penyakit katastropik di 10 rumah sakit selama 3 bulan (Januari–Maret 2012. Analisis data dilakukan secara deskriptif. Hasil: Hasil penelitian menunjukkan bahwa pasien Jamkesmas yang dirawat dengan kasus katastropik terdiri dari penyakit jantung sebesar37,11%, penyakit kanker 23,54% dan sisanya sebesar 39,35% pasien penyakit stroke. Kesimpulan: Biaya pengobatan rawat inap berdasarkan tarif rumah sakit kelas A jauh lebih besar dibandingkan kelas B dan RS Khusus, biaya klaim berdasarkan INA-CBGs jauh lebih besar di rumah sakit kelas A dibanding kelas B dan RS Khusus. Komponen biaya yang banyak peruntukannya adalah biaya akomodasi, tindakan ruangan, pemeriksaan laboratorium, tindakan intervensi nonbedah untuk jantung, tindakan operasi untuk kanker serta biaya obat-obatan. Biaya penggantian klaim penyakit katastropik berdasarkan INA CBGs lebih besar dibandingkan dengan biaya riil berdasarkan tarif rumah sakit, sehingga untuk penyakit katastropik rumah sakit tidak merugi. Untuk itu pelaksanaan kebijakan rujukan berjenjang bagi peserta Jamkesmas harus diawasi secara ketat sehingga pelayanan kesehatan bagi penduduk miskin menjadi lebih terjamin

  7. American alliances and nuclear non-proliferation. The end of nuclear weapon activities of US allies; Amerikanische Allianzen und nukleare Nichtverbreitung. Die Beendigung von Kernwaffenaktivitaeten bei Verbuendeten der USA

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Jonas

    2016-07-01

    Jonas Schneider tackles a question that is of great interest both to scholars of nuclear proliferation and to practitioners of nonproliferation diplomacy: Why do some political leaders of U.S. allies agree to abandon their nation's nuclear weapons activities, while others - who are often members of the same allied government and sometimes even of the same political party - steadfastly reject such a course reversal? Our existing stock of theories does not fare well in accounting for this important variation in leaders' attitudes. To solve this puzzle, Schneider develops an innovative theory that draws on the individual status conceptions of allied political leaders. Subsequently, the author undertakes to test his theory using four thoroughly researched case studies, and he derives important lessons for international nonproliferation diplomacy toward the Middle East and Northeast Asia.

  8. Rezension von: Ina E. Bieber: Frauen in der Politik. Einflussfaktoren auf weibliche Kandidaturen zum Deutschen Bundestag. Wiesbaden: Springer VS 2013.

    Directory of Open Access Journals (Sweden)

    Regina Weber

    2014-03-01

    Full Text Available Ina E. Bieber untersucht in ihrer Dissertation die Einflussfaktoren für erfolgreiche Bundestagskandidaturen von Frauen. Anhand von Längsschnitt- und Querschnittsdaten analysiert sie Faktoren auf der Mikroebene wie individuelle Eigenschaften und Dispositionen sowie Faktoren auf der Makroebene wie Partei- und Wahlsystemeinflüsse. Vor allem letztere wirken sich signifikant auf die Wahlchancen von Frauen aus. Allein das Geschlecht ist kein signifikanter Faktor für den Wahlerfolg zum Bundestag – vor allem die Zugehörigkeit zu Parteien des linken Spektrums und Kandidaturen auf Listenplätzen zeitigen für Frauen größere Chancen, erfolgreich zu kandidieren. Bei den individuellen Faktoren sind erwartete geschlechterspezifische Effekte, zum Beispiel durch Familienstand etc., nicht aufgetreten.

  9. Sub-wavelength InAs quantum dot micro-disk lasers epitaxially grown on exact Si (001) substrates

    Science.gov (United States)

    Wan, Yating; Li, Qiang; Liu, Alan Y.; Chow, Weng W.; Gossard, Arthur C.; Bowers, John E.; Hu, Evelyn L.; Lau, Kei May

    2016-05-01

    Subwavelength micro-disk lasers (MDLs) as small as 1 μm in diameter on exact (001) silicon were fabricated using colloidal lithography. The micro-cavity gain medium incorporating five-stacked InAs quantum dot layers was grown on a high crystalline quality GaAs-on-V-grooved-Si template with no absorptive intermediate buffers. Under continuous-wave optical pumping, the MDLs on silicon exhibit lasing in the 1.2-μm wavelength range with low thresholds down to 35 μW at 10 K. The MDLs compare favorably with devices fabricated on native GaAs substrates and state-of-the-art work reported elsewhere. Feasibility of device miniaturization can be projected by size-dependent lasing characteristics. The results show a promising path towards dense integration of photonic components on the mainstream complementary metal-oxide-semiconductor platform.

  10. Growth of InAs quantum dots on vicinal GaAs substrates by molecular beam epitaxy

    Science.gov (United States)

    Weir, Nicholas; Yao, Ruizhe; Lee, Chi-Sen; Guo, Wei

    2016-10-01

    Previous work shows the benefits of using vicinal substrates but there is currently a gap in the experimental studies of the effects under different MBE growth conditions. To fully realize controllable growth while using a vicinal substrate, we systematically explore and discuss the mechanism behind the dependence of the optical characteristics of MBE grown InAs QD ensembles with different growth parameters on a vicinal substrate. In addition, the potential improvement in optical quality with a vicinal substrate over an on-axis is demonstrated and an investigation into applying a two-step growth procedure on a vicinal substrate is conducted. Photoluminescence of the grown QD ensembles shows that increasing V/III ratio increased wavelength and decreased FWHM. Decreasing substrate temperature increased wavelength and FWHM. Utilizing the two-step growth method increased both wavelength and FWHM with increased interruption time.

  11. Influence of GaAs Substrate Orientation on InAs Quantum Dots: Surface Morphology, Critical Thickness, and Optical Properties

    Directory of Open Access Journals (Sweden)

    Liang BL

    2007-01-01

    Full Text Available AbstractInAs/GaAs heterostructures have been simultaneously grown by molecular beam epitaxy on GaAs (100, GaAs (100 with a 2° misorientation angle towards [01−1], and GaAs (n11B (n = 9, 7, 5 substrates. While the substrate misorientation angle increased from 0° to 15.8°, a clear evolution from quantum dots to quantum well was evident by the surface morphology, the photoluminescence, and the time-resolved photoluminescence, respectively. This evolution revealed an increased critical thickness and a delayed formation of InAs quantum dots as the surface orientation departed from GaAs (100, which was explained by the thermal-equilibrium model due to the less efficient of strain relaxation on misoriented substrate surfaces.

  12. Influence of the oxide layer for growth of self-assisted InAs nanowires on Si(111

    Directory of Open Access Journals (Sweden)

    Aagesen Martin

    2011-01-01

    Full Text Available Abstract The growth of self-assisted InAs nanowires (NWs by molecular beam epitaxy (MBE on Si(111 is studied for different growth parameters and substrate preparations. The thickness of the oxide layer present on the Si(111 surface is observed to play a dominant role. Systematic use of different pre-treatment methods provides information on the influence of the oxide on the NW morphology and growth rates, which can be used for optimizing the growth conditions. We show that it is possible to obtain 100% growth of vertical NWs and no parasitic bulk structures between the NWs by optimizing the oxide thickness. For a growth temperature of 460°C and a V/III ratio of 320 an optimum oxide thickness of 9 ± 3 Å is found.

  13. GaAs-based long-wavelength InAs bilayer quantum dots grown by molecular beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    Zhu Yan; Li Mifeng; He Jifang; Yu Ying; Ni Haiqiao; Xu Yingqiang; Wang Juan; He Zhenhong; Niu Zhichuan

    2011-01-01

    Molecular beam epitaxy growth ofa bilayer stacked InAs/GaAs quantum dot structure on a pure GaAs matrix has been systemically investigated.The influence of growth temperature and the InAs deposition of both layers on the optical properties and morphologies of the bilayer quantum dot (BQD) structures is discussed.By optimizing the growth parameters,InAs BQD emission at 1.436μm at room temperature with a narrower FWHM of 27 meV was demonstrated.The density of QDs in the second layer is around 9 × 109 to 1.4 × 1010 cm-2.The BQD structure provides a useful way to extend the emission wavelength of GaAs-based material for quantum functional devices.

  14. DVOKRATNA PRIMJENA SMANJENIH KOLIČINA HERBICIDA U ŠPINATU – PRINOS «MINOR USES» UPORABI

    OpenAIRE

    Žarković, Ana; Barić, Klara; Žutić, Ivanka; Ostojić, Zvonimir

    2008-01-01

    Tijekom 2005. godine na lokaciji u Šašinovečkom Lugu postavljen je pokus u usjevu špinata (Spinacea oleracea L.) sa svrhom provjere učinka dvokratne primjene smanjenih količina kombinacije herbicida na korove. Istražen je učinak sljedećih kombinacija herbicida: lenacil 640 g a.t./ha pre-em + (dezmedifam+fenmedifam+etofumesat 63+49+77 g a.t./ha) post-em; s-dimetenamid 576 g a.t./ha pre-em; (dezmedifam+fenmedifam 40+40 g a.t./ha)+ (dezmedifam+fenmedifam 56+56 g a.t./ha) post-em; (dezmedifam +fe...

  15. Electronic structure of reconstructed InAs(001) surfaces - identification of bulk and surface bands based on their symmetries

    Science.gov (United States)

    Olszowska, Natalia; Kolodziej, Jacek J.

    2016-02-01

    Using angle-resolved photoelectron spectroscopy (ARPES) band structures of indium- and arsenic-terminated InAs(001) surfaces are investigated. These surfaces are highly reconstructed, elementary cells of their lattices contain many atoms in different chemical configurations, and moreover, they are composed of domains having related but different reconstructions. These domain-type surface reconstructions result in the reciprocal spaces containing regions with well-defined k→∥-vector and regions with not-well-defined one. In the ARPES spectra most of the surface related features appear as straight lines in the indeterminate k→∥-vector space. It is shown that, thanks to differences in crystal and surface symmetries, the single photon energy ARPES may be successfully used for classification of surface and bulk bands of electronic states on complex, highly reconstructed surfaces instead of the most often used variable photon energy studies.

  16. Utjecaj načina zrenja na udjel vode u bezmasnoj tvari i na udjel masti u siru Trapistu

    OpenAIRE

    Kirin, Slavko

    2001-01-01

    U radu je istraživan utjecaj načina zrenja na udjel vode u bezmasnoj tvari i na udjel masti u siru Trapistu. U sadašnjoj proizvodnji (Lura, Tvornica Bjelovar), sir Trapist zrije na prirodan način s oblikovanjem kore, te vakuumski upakiran u termoskupljajuče plastične vrećice, čime se dobije sir bez kore. Utvrđeno je da spomenuti načini zrenja uvjetuju signifikantne razlike u udjelu vode u bezmasnoj tvari sira. On je 5,34 % viši kod sira Trapista u vrećici u odnosu na sir Trapist s korom. Udje...

  17. Comparative study of low temperature growth of InAs and InMnAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Placidi, E [Istituto di Struttura della Materia, CNR, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Zallo, E; Arciprete, F; Fanfoni, M; Patella, F; Balzarotti, A, E-mail: ernesto.placidi@ism.cnr.it [Dipartimento di Fisica, Universita di Roma ' Tor Vergata' , via della Ricerca Scientifica 1, I-00133 Roma (Italy)

    2011-05-13

    The evolution of InAs and In{sub 0.85}Mn{sub 0.15}As quantum dots grown at 270 deg. C is studied as a function of coverage. We show that, in contrast to what occurs at high temperature, the two-dimensional to three-dimensional transition is not abrupt but rather slow. This is due to the finding that part of the deposited material also contributes to the wetting layer growth after quantum dot formation. This aspect is particularly accentuated in In{sub 0.85}Mn{sub 0.15}As deposition. The Voronoi area analysis reveals a significant spatial correlation between islands.

  18. Use of BABA and INA as activators of a primed state in the common bean (Phaseolus vulgaris L..

    Directory of Open Access Journals (Sweden)

    Keren eMartínez-Aguilar

    2016-05-01

    Full Text Available To survive in adverse conditions, plants have evolved complex mechanisms that prime their defense system to respond and adapt to stresses. Their competence to respond to such stresses fundamentally depends on its capacity to modulate the transcriptome rapidly and specifically. Thus, chromatin dynamics is a mechanism linked to transcriptional regulation and enhanced defense in plants. For example, in Arabidopsis, priming of the SA-dependent defense pathway is linked to histone lysine methylation. Such modifications could create a memory of the primary infection that is associated with an amplified gene response upon exposure to a second stress-stimulus. In addition, the priming status of a plant for induced resistance can be inherited to its offspring. However, analyses on the molecular mechanisms of generational and transgenerational priming in the common bean (Phaseolus vulagris L., an economically important crop, are absent.Here, we provide evidence that resistance to P. syringae pv. phaseolicola infection was induced in the common bean with the synthetic priming activators BABA and INA. Resistance was assessed by evaluating symptom appearance, pathogen accumulation, changes in gene expression of defense genes, as well as changes in the H3K4me3 and H3K36me3 marks at the promoter-exon regions of defense-associated genes. We conclude that defense priming in the common bean occurred in response to BABA and INA and that these synthetic activators primed distinct genes for enhanced disease resistance.We hope that an understanding of the molecular changes leading to defense priming and pathogen resistance will provide valuable knowledge for producing disease-resistant crop varieties by exposing parental plants to priming activators, as well as to the development of novel plant protection chemicals that stimulate the plant's inherent disease resistance mechanisms.

  19. Accountability and non-proliferation nuclear regime: a review of the mutual surveillance Brazilian-Argentine model for nuclear safeguards; Accountability e regime de nao proliferacao nuclear: uma avaliacao do modelo de vigilancia mutua brasileiro-argentina de salvaguardas nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Xavier, Roberto Salles

    2014-08-01

    The regimes of accountability, the organizations of global governance and institutional arrangements of global governance of nuclear non-proliferation and of Mutual Vigilance Brazilian-Argentine of Nuclear Safeguards are the subject of research. The starting point is the importance of the institutional model of global governance for the effective control of non-proliferation of nuclear weapons. In this context, the research investigates how to structure the current arrangements of the international nuclear non-proliferation and what is the performance of model Mutual Vigilance Brazilian-Argentine of Nuclear Safeguards in relation to accountability regimes of global governance. For that, was searched the current literature of three theoretical dimensions: accountability, global governance and global governance organizations. In relation to the research method was used the case study and the treatment technique of data the analysis of content. The results allowed: to establish an evaluation model based on accountability mechanisms; to assess how behaves the model Mutual Vigilance Brazilian-Argentine Nuclear Safeguards front of the proposed accountability regime; and to measure the degree to which regional arrangements that work with systems of global governance can strengthen these international systems. (author)

  20. Nuclear proliferation and civilian nuclear power: report of the Nonproliferation Alternative Systems Assessment Program. Volume IX. Reactor and fuel cycle descriptions

    Energy Technology Data Exchange (ETDEWEB)

    1979-12-01

    The Nonproliferation Alternative Systems Assessment Program (NASAP) has characterized and assessed various reactor/fuel-cycle systems. Volume IX provides, in summary form, the technical descriptions of the reactor/fuel-cycle systems studied. This includes the status of the system technology, as well as a discussion of the safety, environmental, and licensing needs from a technical perspective. This information was then used in developing the research, development, and demonstration (RD and D) program, including its cost and time frame, to advance the existing technology to the level needed for commercial use. Wherever possible, the cost data are given as ranges to reflect the uncertainties in the estimates. Volume IX is divided into three sections: Chapter 1, Reactor Systems; Chapter 2, Fuel-Cycle Systems; and the Appendixes. Chapter 1 contains the characterizations of the following 12 reactor types: light-water reactor; heavy-water reactor; water-cooled breeder reactor; high-temperature gas-cooled reactor; gas-cooled fast reactor; liquid-metal fast breeder reactor; spectral-shift-controlled reactor; accelerator-driven reactor; molten-salt reactor; gaseous-core reactor; tokamak fusion-fisson hybrid reactor; and fast mixed-spectrum reactor. Chapter 2 contains similar information developed for fuel-cycle facilities in the following categories: mining and milling; conversion and enrichment; fuel fabrication; spent fuel reprocessing; waste handling and disposal; and transportation of nuclear materials.

  1. Cooperation in Nuclear Waste Management, Radiation Protection, Emergency Preparedness, Reactor Safety and Nuclear Non-Proliferation with the Russian Federation, Ukraine, Armenia, Georgia and Belarus.

    Energy Technology Data Exchange (ETDEWEB)

    Dassen, Lars van; Andersson, Sarmite; Bejarano, Gabriela; Delalic, Zlatan; Ekblad, Christer; German, Olga; Grapengiesser, Sten; Karlberg, Olof; Olsson, Kjell; Sandberg, Viviana; Stenberg, Tor; Turner, Roland; Zinger, Irene

    2010-06-15

    The Swedish Radiation Safety Authority (SSM) is trusted with the task of implementing Sweden's bilateral cooperation with Russia, Ukraine, Georgia, Belarus and Armenia in the fields of reactor safety, nuclear waste management, nuclear non-proliferation as well as radiation protection and emergency preparedness. In these fields, SSM also participates in a number of projects financed by the European Union. This report gives an overview of the cooperation projects in 2009 as well as the framework in which they are performed. Summaries of each project are given in an Appendix. The project managers in the Section for Cooperation and Development in the Department of International Affairs are responsible for the cooperation projects and the implementation of the bilateral programmes. But the positive outcome of the projects is also dependent on a large number of experts at SSM who work with the regulatory functions in the nuclear and radiation protection fields in a Swedish context as well as on external consultants. Together, their experience is invaluable for the implementation of the projects. But the projects also give experience of relevance for the SSM staff.

  2. Temperature characteristics of epitaxially grown InAs quantum dot micro-disk lasers on silicon for on-chip light sources

    Science.gov (United States)

    Wan, Yating; Li, Qiang; Liu, Alan Y.; Gossard, Arthur C.; Bowers, John E.; Hu, Evelyn L.; Lau, Kei May

    2016-07-01

    Temperature characteristics of optically pumped micro-disk lasers (MDLs) incorporating InAs quantum dot active regions are investigated for on-chip light sources. The InAs quantum dot MDLs were grown on V-groove patterned (001) silicon, fully compatible with the prevailing complementary metal oxide-semiconductor technology. By combining the high-quality whispering gallery modes and 3D confinement of injected carriers in quantum dot micro-disk structures, we achieved lasing operation from 10 K up to room temperature under continuous optical pumping. Temperature dependences of the threshold, lasing wavelength, slope efficiency, and mode linewidth are examined. An excellent characteristic temperature To of 105 K has been extracted.

  3. Probing into hybrid organic-molecule and InAs quantum-dots nanosystem with multistacked dots-in-a-well units

    DEFF Research Database (Denmark)

    Chen, Miaoxiang Max; Kobashi, Kazufumi

    2012-01-01

    Hybridizing air-stable organic-molecules with advanced III-V semiconductor quantum-dots (QDs) structures can be utilized to create a new generation of biochemical sensing devices. In order to enhance their optical performances, the active regions in these QDs structures commonly consist...... of multistacked dots-in-a-well (DWELL) units. The effects of grafted molecules on the performances of the QDs structures with multistacked DWELLs, however, still remain unclear. Here, we show the significant improvements in the optical properties of InAs QDs in a hybrid nanosystem obtained by grafting...... biocompatible diazonium salt compound (amine donor) atop InAs QDs structure. Since its interface between the QDs structure and molecular monolayer retains an uncontaminated and non-oxidized condition, the nanosystem is an ideal platform to study the intrinsic properties of charge-carrier transport inside...

  4. Alloy formation during molecular beam epitaxy growth of Si-doped InAs nanowires on GaAs[111]B.

    Science.gov (United States)

    Davydok, Anton; Rieger, Torsten; Biermanns, Andreas; Saqib, Muhammad; Grap, Thomas; Lepsa, Mihail Ion; Pietsch, Ullrich

    2013-08-01

    Vertically aligned InAs nanowires (NWs) doped with Si were grown self-assisted by molecular beam epitaxy on GaAs[111]B substrates covered with a thin SiO x layer. Using out-of-plane X-ray diffraction, the influence of Si supply on the growth process and nanostructure formation was studied. It was found that the number of parasitic crystallites grown between the NWs increases with increasing Si flux. In addition, the formation of a Ga0.2In0.8As alloy was observed if the growth was performed on samples covered by a defective oxide layer. This alloy formation is observed within the crystallites and not within the nanowires. The Ga concentration is determined from the lattice mismatch of the crystallites relative to the InAs nanowires. No alloy formation is found for samples with faultless oxide layers.

  5. Defect-free zinc-blende structured InAs nanowires realized by in situ two V/III ratio growth in molecular beam epitaxy.

    Science.gov (United States)

    Zhang, Zhi; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin

    2015-08-07

    In this study, we devised a two-V/III-ratio procedure to control the Au-assisted growth of defect-free InAs nanowires in molecular beam epitaxy. The demonstrated two V/III ratio procedure consists of a first high V/III ratio growth step to prepare the nanowire foundation on the substrate surface, followed by a low V/III ratio step to induce the nanowire growth. By manipulating the V/III ratios in different steps, we have achieved the controlled growth of pure defect-free zinc-blende structured InAs nanowires on the GaAs {1̄1̄1̄} substrates. This study provides an approach to control not only the crystal structure of semiconductor nanowires, but also their structural qualities.

  6. INaP selective inhibition reverts precocious inter- and motorneurons hyperexcitability in the Sod1-G93R zebrafish ALS model

    Science.gov (United States)

    Benedetti, Lorena; Ghilardi, Anna; Rottoli, Elsa; De Maglie, Marcella; Prosperi, Laura; Perego, Carla; Baruscotti, Mirko; Bucchi, Annalisa; Del Giacco, Luca; Francolini, Maura

    2016-01-01

    The pathogenic role of SOD1 mutations in amyotrophic lateral sclerosis (ALS) was investigated using a zebrafish disease model stably expressing the ALS-linked G93R mutation. In addition to the main pathological features of ALS shown by adult fish, we found remarkably precocious alterations in the development of motor nerve circuitry and embryo behavior, and suggest that these alterations are prompted by interneuron and motor neuron hyperexcitability triggered by anomalies in the persistent pacemaker sodium current INaP. The riluzole-induced modulation of INaP reduced spinal neuron excitability, reverted the behavioral phenotypes and improved the deficits in motor nerve circuitry development, thus shedding new light on the use of riluzole in the management of ALS. Our findings provide a valid phenotype-based tool for unbiased in vivo drug screening that can be used to develop new therapies. PMID:27079797

  7. Temperature characteristics of epitaxially grown InAs quantum dot micro-disk lasers on silicon for on-chip light sources

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Yating; Li, Qiang; Lau, Kei May, E-mail: eekmlau@ust.hk [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Liu, Alan Y. [Materials Department, University of California Santa Barbara, Santa Barbara, California 93106 (United States); Gossard, Arthur C.; Bowers, John E. [Materials Department, University of California Santa Barbara, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106 (United States); Hu, Evelyn L. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2016-07-04

    Temperature characteristics of optically pumped micro-disk lasers (MDLs) incorporating InAs quantum dot active regions are investigated for on-chip light sources. The InAs quantum dot MDLs were grown on V-groove patterned (001) silicon, fully compatible with the prevailing complementary metal oxide-semiconductor technology. By combining the high-quality whispering gallery modes and 3D confinement of injected carriers in quantum dot micro-disk structures, we achieved lasing operation from 10 K up to room temperature under continuous optical pumping. Temperature dependences of the threshold, lasing wavelength, slope efficiency, and mode linewidth are examined. An excellent characteristic temperature T{sub o} of 105 K has been extracted.

  8. Ab initio calculations of polarization, piezoelectric constants, and elastic constants of InAs and InP in the wurtzite phase

    Energy Technology Data Exchange (ETDEWEB)

    Hajlaoui, C., E-mail: hajlaouic@yahoo.fr; Pedesseau, L. [Université Européenne de Bretagne (France); Raouafi, F.; Ben Cheikh Larbi, F. [Université de Carthage, Laboratoire de Physico-Chimie, des Microstructures et des Microsystémes, Institut Préparatoire aux Études Scientifiques et Techniques (Tunisia); Even, J.; Jancu, J.-M. [Université Européenne de Bretagne (France)

    2015-08-15

    We report first-principle density functional calculations of the spontaneous polarization, piezoelectric stress constants, and elastic constants for the III–V wurtzite structure semiconductors InAs and InP. Using the density functional theory implemented in the VASP code, we obtain polarization values–0.011 and–0.013 C/m{sup 2}, and piezoelectric constants e{sub 33} (e{sub 31}) equal to 0.091 (–0.026) and 0.012 (–0.081) C/m{sup 2} for structurally relaxed InP and InAs respectively. These values are consistently smaller than those of nitrides. Therefore, we predict a smaller built-in electric field in such structures.

  9. Prediction of phonon thermal transport in thin GaAs, InAs and InP nanowires by molecular dynamics simulations: influence of the interatomic potential.

    Science.gov (United States)

    Carrete, J; Longo, R C; Gallego, L J

    2011-05-06

    A number of different potentials are currently being used in molecular dynamics simulations of semiconductor nanostructures. Confusion can arise if an inappropriate potential is used. To illustrate this point, we performed direct molecular dynamics simulations to predict the room temperature lattice thermal conductivity λ of thin GaAs, InAs and InP nanowires. In each case, simulations performed using the classical Harrison potential afforded values of λ about an order of magnitude smaller than those obtained using more elaborate potentials (an Abell-Tersoff, as parameterized by Hammerschmidt et al for GaAs and InAs, and a potential of Vashishta type for InP). These results will be a warning to those wishing to use computer simulations to orient the development of quasi-one-dimensional systems as heat sinks or thermoelectric devices.

  10. Prediction of phonon thermal transport in thin GaAs, InAs and InP nanowires by molecular dynamics simulations: influence of the interatomic potential

    Energy Technology Data Exchange (ETDEWEB)

    Carrete, J; Longo, R C; Gallego, L J, E-mail: jesus.carrete@usc.es [Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

    2011-05-06

    A number of different potentials are currently being used in molecular dynamics simulations of semiconductor nanostructures. Confusion can arise if an inappropriate potential is used. To illustrate this point, we performed direct molecular dynamics simulations to predict the room temperature lattice thermal conductivity {lambda} of thin GaAs, InAs and InP nanowires. In each case, simulations performed using the classical Harrison potential afforded values of {lambda} about an order of magnitude smaller than those obtained using more elaborate potentials (an Abell-Tersoff, as parameterized by Hammerschmidt et al for GaAs and InAs, and a potential of Vashishta type for InP). These results will be a warning to those wishing to use computer simulations to orient the development of quasi-one-dimensional systems as heat sinks or thermoelectric devices.

  11. Solução concentrada de albumina eqüina na fluidoterapia em eqüinos com desidratação leve a moderada

    OpenAIRE

    2008-01-01

    Avaliou-se o efeito da solução concentrada de albumina eqüina diluída a 5% em solução fisiológica (SF) durante fluidoterapia em eqüinos, após indução de desidratação leve a moderada, utilizando-se cinco eqüinos adultos, sem alterações clínicas. Cada animal passou por dois protocolos de fluidoterapia: apenas com SF (metade sob pressão e metade em fluxo contínuo - grupo-controle); com solução de albumina eqüina e SF (apenas em fluxo contínuo - grupo experimental). Avaliaram-se peso, exame físic...

  12. Capacitance-voltage profile characteristics of Schottky barrier structure with InAs quantum dots grown on InAlAs/InP(001)

    Energy Technology Data Exchange (ETDEWEB)

    Baira, M. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Departement de Physique, Faculte des Sciences, 5019 Monastir (Tunisia); Ajjel, R. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Departement de Physique, Faculte des Sciences, 5019 Monastir (Tunisia)]. E-mail: ridha.ajjel@fsm.rnu.tn; Maaref, H. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Departement de Physique, Faculte des Sciences, 5019 Monastir (Tunisia); Salem, B. [Laboratoire de Physique de la Matiere-LPM (UMR-CNRS 5511), INSA de Lyon, Batiment Blaise Pascal, 7 Avenue J. Capelle, 69621 Villeurbanne (France); Bremond, G. [Laboratoire de Physique de la Matiere-LPM (UMR-CNRS 5511), INSA de Lyon, Batiment Blaise Pascal, 7 Avenue J. Capelle, 69621 Villeurbanne (France); Gendry, M. [Laboratoire d' Electronique, Optoelectronique et Microsystemes-LEOM (UMR-CNRS 5512), Ecole Centrale de Lyon, 36 Avenue G. de Collongue, 69134 Ecully (France); Marty, O. [Laboratoire d' Electronique-LENAC, Universite Lyon 1, F-69622 Villeurbanne, Lyon (France)

    2006-03-15

    Capacitance-voltage, C(V) studies have been carried out on Schottky barrier structure containing a sheet of self-organized InAs quantum dots (QDs) grown on InAlAs lattice matched to InP in order to deduce the electrical properties of the QDs. Three electron levels have been detected in n-type material, and were attributed to the s ground, the p excited, and the d excited states. Some parameters of the structure, such as the position of the InAs QD plane, the electron concentration in the QDs and an approximate QD height were deduced from the C(V) profile analysis. These results are in good agreement with the transmission electron microscopy (TEM) study realized on the structure.

  13. Evolution of InAs islands in the Stranski-Krastanow mode of InAs/GaAs(001) fabricated using molecular beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    WU Ju; JIN Pen; L(U) Xiao-jing; JIAO Yu-heng; WANG Zhan-guo

    2007-01-01

    Based on step-by-step observation using atomic force microscope, two distinctive successive phases were distinguished in accordance with evolution of the three-dimensional InAs islands during the Stranski-Krastanow mode of the InAs/GaAs(001) system fabricated using molecularbeam epitaxy. The initial phase is consistent with a power law, and the latter phase is a comparatively gradual one.

  14. InAs pixel matrix detectors fabricated by diffusion of Zn in a metal-organic vapour-phase epitaxy reactor

    Energy Technology Data Exchange (ETDEWEB)

    Saeynaetjoki, A. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland)]. E-mail: antti.saynatjoki@tkk.fi; Kostamo, P. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Sormunen, J. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Riikonen, J. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Lankinen, A. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Lipsanen, H. [Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 HUT (Finland); Andersson, H. [Oxford Instruments Analytical Oy (United Kingdom); Banzuzi, K. [Oxford Instruments Analytical Oy (United Kingdom); Nenonen, S. [Oxford Instruments Analytical Oy (United Kingdom); Sipilae, H. [Oxford Instruments Analytical Oy (United Kingdom); Vaijaervi, S. [Oxford Instruments Analytical Oy (United Kingdom); Lumb, D. [Science Payload and Advanced Concepts Office, ESA/ESTEC, Nordwijk (Netherlands)

    2006-07-01

    We introduce a zinc diffusion process to fabricate an InAs-based detector matrix using an atmospheric pressure metal-organic vapour-phase epitaxy reactor. Current-voltage characteristics are measured and different diffusion parameters are experimented. Spectral alpha radiation response of the diode is reported. To our knowledge, this is the first time that InAs was used as an alpha particle detector.

  15. Thermal conductivity of InAs quantum dot stacks using AlAs strain compensating layers on InP substrate

    Energy Technology Data Exchange (ETDEWEB)

    Salman, S. [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France); Folliot, H., E-mail: herve.folliot@insa-rennes.fr [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France); Le Pouliquen, J.; Chevalier, N.; Rohel, T.; Paranthoeen, C.; Bertru, N. [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France); Labbe, C. [CIMAP, CEA/UMR CNRS 6252/ENSICAEN/Universite de Caen Basse Normandie, 6, Boulevard Marechal Juin, 14050 Caen Cedex 4 (France); Letoublon, A.; Le Corre, A. [Universite Europeenne de Bretagne, CNRS, Laboratoire FOTON, INSA, 20 Avenue des buttes de Coeesmes, 35708 Rennes, Cedex 7 (France)

    2012-06-25

    Highlights: Black-Right-Pointing-Pointer The thermal conductivity of InAs on InP (1 1 3)B quantum dots stacks is measured. Black-Right-Pointing-Pointer The growth of a close stack of 100 layers of InAs using AlAs strain compensating layers is presented. Black-Right-Pointing-Pointer New data on the thermal conductivity of InP n-doped susbtrate are given. - Abstract: The growth and thermal conductivity of InAs quantum dot (QD) stacks embedded in GaInAs matrix with AlAs compensating layers deposited on (1 1 3)B InP substrate are presented. The effect of the strain compensating AlAs layer is demonstrated through Atomic Force Microscopy (AFM) and X-ray diffraction structural analysis. The thermal conductivity (2.7 W/m K at 300 K) measured by the 3{omega} method reveals to be clearly reduced in comparison with a bulk InGaAs layer (5 W/m K). In addition, the thermal conductivity measurements of S doped InP substrates and the SiN insulating layer used in the 3{omega} method in the 20-200 Degree-Sign C range are also presented. An empirical law is proposed for the S doped InP substrate, which slightly differs from previously presented results.

  16. Efficient Exciton Transfer from In0.35Ga0.65As Template into InAs Quantum Dots Grown on GaAs (311)B Substrates

    Institute of Scientific and Technical Information of China (English)

    WANG Fang-Zhen; CHEN Zhang-Hai; GONG Qian; R. N(o)tzel; BAI Li-Hui; SHEN Xue-Chu

    2006-01-01

    @@ Atomic force microscopy (AFM) and power-dependent micro-photoluminescence (μ-PL) spectroscopy are used to study the structure and exciton energy states in InAs quantum dots (QDs) grown on an In0.35 Ga0.65As template on GaAs (311)B. The In0.35Ga0.65As template, consisting of a two-dimensionally modulated layer of closely packed connected cells, has a remarkable effect on the optical properties of the InAs QDs. By comparing the emission spectra of the samples without and with InAs QDs and the work carried out by Gong et al. [J. Cryst.Growth 251 (2003) 150; Appl. Phys. Lett. 81 (2002) 3254] we conclude that the existence of the In0.35Ga0.65As template enhances the photo-absorption and therefore the exciton emission from the QDs due to efficient exciton transfer from the template into the QDs. Furthermore, the PL emission from the QDs clearly reveals four discrete energy levels, S, P, D, and F with increasing excitation power.

  17. Muscle cell migrations of C. elegans are mediated by the alpha-integrin INA-1, Eph receptor VAB-1, and a novel peptidase homologue MNP-1.

    Science.gov (United States)

    Tucker, Morgan; Han, Min

    2008-06-15

    Cell migration is a fundamental process occurring during embryonic development and tissue morphogenesis. In the nematode Caenorhabditis elegans, morphogenesis of the body-wall musculature involves short-range migrations of 81 embryonic muscle cells from the lateral surface of the embryo towards the dorsal and ventral midlines. This study shows that mutations in ina-1 (alpha-integrin), as well as vab-1 (Eph receptor), and vab-2 (ephrin), display defects in embryonic muscle cell migration. Furthermore, an RNAi-based enhancer screen in an ina-1 weak loss-of-function background identified mnp-1 (matrix non-peptidase homologue-1) as a previously uncharacterized gene required for promoting proper migration of the embryonic muscle cells. mnp-1 encodes a membrane associated metalloproteinase homologue that is predicted to be catalytically inactive. Our data suggest that MNP-1 is expressed in migrating muscle cells and localizes to the plasma membrane with the non-peptidase domain exposed to the extra-cellular environment. Double-mutant analysis between mnp-1(RNAi), ina-1, and vab-1 mutations; as well as tissue specific rescue experiments; indicated that each of these gene products function predominantly independent of each other and from different cell types to affect muscle cell migration. Together these results suggest complex interactions between the adjacent epidermal, neuronal, and muscle cells are required to promote proper muscle cell migration during embryogenesis.

  18. Anna Kareņina mūsdienu literatūrā: no anekdotes līdz romānam-apgreidam

    OpenAIRE

    Vinčugova, Natālija

    2009-01-01

    Bakalaura darbs „Anna Kareņina mūsdienu literatūrā: no anekdotes līdz romānam – apgreidam” – ir mēģinājums uz Annas Kareņinas tēla piemēra izanalizēt „klasisko” daiļdarbu popularitāti starp mūsdienu autoriem, kuru uztveres un izpratnes problēma mūsdienu sabiedrībā ir ļoti aktuāla. Pētījums tiek veikts uz anekdošu teksta analīzes, kuri subjekta vai objekta lomā izmanto Annas Kareņinas tēlu, kā arī Ļva Nikolajeviča „Anna Kareņina” un Lilijas Kim „Aņa Kareņina” romānu pamata. Darbā arī ir ...

  19. Anna Kareņina mūsdienu literatūrā: no anekdotes līdz romānam-apgreidam

    OpenAIRE

    Vinčugova, Natālija

    2009-01-01

    Bakalaura darbs „Anna Kareņina mūsdienu literatūrā: no anekdotes līdz romānam – apgreidam” – ir mēģinājums uz Annas Kareņinas tēla piemēra izanalizēt „klasisko” daiļdarbu popularitāti starp mūsdienu autoriem, kuru uztveres un izpratnes problēma mūsdienu sabiedrībā ir ļoti aktuāla. Pētījums tiek veikts uz anekdošu teksta analīzes, kuri subjekta vai objekta lomā izmanto Annas Kareņinas tēlu, kā arī Ļva Nikolajeviča „Anna Kareņina” un Lilijas Kim „Aņa Kareņina” romānu pamata. Darbā arī ir ...

  20. Optical Characteristics of InAs Quantum Dots on GaAs Matrix by Using Various InGaAs Structures

    Institute of Scientific and Technical Information of China (English)

    KONG Lingmin; CAI Jiafa; WU Zhengyun; GONG Zheng; FANG Zhidan; NIU Zhichuan

    2006-01-01

    The effects of various InGaAs layers on the structural and optical properties of InAs self-assembled quantum dots(QDs) grown by molecular-beam epitaxy (MBE) were investigated. The emission wavelength of 1317 nm was obtained by embedding InAs QDs in InGaAs/GaAs quantum well. The temperature-dependent and timed-resolved photoluminescence (TDPL and TRPL) were used to study the dynamic characteristics of carriers. InGaAs cap layer may improve the quality of quantum dots for the strain relaxation around QDs, which results in a stronger PL intensity and an increase of PL peak lifetime up to 170 K. We found that InGaAs buffer layer may reduce the PL peak lifetime of InAs QDs, which is due to the buffer layer accelerating the carrier migration. The results also show that InGaAs cap layer can increase the temperature point when the thermal reemission and nonradiative recombination contribute significantly to the carrier dynamics.

  1. Dual-polarization light emission from InAs quantum dots in a annular photonic crystal cavity

    CERN Document Server

    Jiang, Liyong; Wu, Hong; Zhang, Wei; Su, Wei; Li, Xiangyin

    2014-01-01

    The annular photonic crystals have been regarded as a satisfactory candidate to realize dual-polarization photonic device. In this letter, we focus our attention on the study of annular photonic crystal cavity to verify its application in light emission. We proposed a two-dimensional photonic crystal model with annular air units and a point-line defect to construct a cavity for the enhancement of light emission of InAs quantum dots. With the help of global optimization method, we have obtained an annular photonic crystal cavity design which can show a high in-plane quality factor of about 1.3*105 and 2.8*106 for transverse electric and transverse magnetic polarizations, respectively. Based on the Electron Beam Lithography and Reactive Ion Etching techniques, such cavity pattern was transferred into the top of InAs/GaAs active layer. The photoluminescence spectra of sample demonstrated clear light emission at around 1.3 um for both polarizations. Such dual-polarization light emitter has potential applications ...

  2. Towards site controlled growth of InAs quantum dots on patterned GaAs by microsphere photolithography

    Energy Technology Data Exchange (ETDEWEB)

    Rengstl, Ulrich; Koroknay, Elisabeth; Rossbach, Robert; Jetter, Michael; Michler, Peter [Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)

    2011-07-01

    To use quantum dots (QDs) in single photon applications, like quantum information processing, we are working on separate addressable, site controlled QDs. For this, we generate surface potential modulations by patterning the GaAs surface before the overgrowth in a metal-organic vapor-phase epitaxy system (MOVPE). Conventional patterning techniques, such as electron beam lithography or site controlled surface oxidation using scanning tunneling microscopy, have the disadvantage of high time consumption. A faster method for prepatterning a large surface uses microsphere photolithography. For partial exposure of UV-sensitive photoresist, we use a hexagonal close-packed microsphere monolayer as an array of microlenses to focus UV-light. We obtained structures with controllable diameters of 300 to 700 nm in the photoresist, which can be used as an etching mask for wet chemical etching to generate holes in the GaAs surface. After this, various steps of post etch cleaning and oxide removal are necessary to obtain a GaAs buffer with low defect density and high optical quality after the following overgrowth. The prepatterning also leads to an increased accumulation of deposited InAs inside the holes, which supports island growth.

  3. Probing the gate--voltage-dependent surface potential of individual InAs nanowires using random telegraph signals.

    Science.gov (United States)

    Salfi, Joe; Paradiso, Nicola; Roddaro, Stefano; Heun, Stefan; Nair, Selvakumar V; Savelyev, Igor G; Blumin, Marina; Beltram, Fabio; Ruda, Harry E

    2011-03-22

    We report a novel method for probing the gate-voltage dependence of the surface potential of individual semiconductor nanowires. The statistics of electronic occupation of a single defect on the surface of the nanowire, determined from a random telegraph signal, is used as a measure for the local potential. The method is demonstrated for the case of one or two switching defects in indium arsenide (InAs) nanowire field effect transistors at temperatures T=25-77 K. Comparison with a self-consistent model shows that surface potential variation is retarded in the conducting regime due to screening by surface states with density Dss≈10(12) cm(-2) eV(-1). Temperature-dependent dynamics of electron capture and emission producing the random telegraph signals are also analyzed, and multiphonon emission is identified as the process responsible for capture and emission of electrons from the surface traps. Two defects studied in detail had capture activation energies of EB≈50 meV and EB≈110 meV and cross sections of σ∞≈3×10(-19) cm2 and σ∞≈2×10(-17) cm2, respectively. A lattice relaxation energy of Sℏω=187±15 meV was found for the first defect.

  4. Magnetoresistance engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates

    Science.gov (United States)

    Fábián, G.; Makk, P.; Madsen, M. H.; Nygârd, J.; Schönenberger, C.; Baumgartner, A.

    2016-11-01

    We present magnetoresistance (MR) experiments on an InAs nanowire quantum dot device with two ferromagnetic sidegates (FSGs) in a split-gate geometry. The wire segment can be electrically tuned to a single dot or to a double dot regime using the FSGs and a backgate. In both regimes we find a strong MR and a sharp MR switching of up to 25% at the field at which the magnetizations of the FSGs are inverted by the external field. The sign and amplitude of the MR and the MR switching can both be tuned electrically by the FSGs. In a double dot regime close to pinch-off we find two sharp transitions in the conductance, reminiscent of tunneling MR (TMR) between two ferromagnetic contacts, with one transition near zero and one at the FSG switching fields. These surprisingly rich characteristics we explain in several simple resonant tunneling models. For example, the TMR-like MR can be understood as a stray-field controlled transitions between singlet and triplet double dot states. Such local magnetic fields are the key elements in various proposals to engineer novel states of matter and may be used for testing electron spin based Bell inequalities.

  5. The role of InAs thickness on the material properties of InAs/GaSb superlattices

    Science.gov (United States)

    Haugan, H. J.; Brown, G. J.; Szmulowicz, F.; Elhamri, S.; Olson, B. V.; Boggess, T. F.; Grazulis, L.

    2011-09-01

    The epitaxial growth parameters optimized for mid-wavelength infrared (MWIR) InAs/GaSb superlattice (SL) growth are not directly applicable for long-wavelength infrared (LWIR) SL growth. We observed a two orders of magnitude drop in the spectral intensity of the measured photoresponse (PR) as the InAs layer thickness in the SL increases from 9 monolayers (MLs) to 16 MLs for a fixed GaSb layer thickness of 7 MLs. However, the theoretically calculated absorption strength decreases only by about a factor of two. So other factors affecting photoresponse, such as carrier mobility and lifetime, are likely responsible for the large drop in the PR of the LWIR SL in this sample set. In fact the measured Hall properties of MWIR and LWIR SLs are very different, with holes as the majority carriers in MWIR SLs and electrons as the majority carriers in LWIR SLs. Therefore we investigated the charge carrier density, carrier mobility, and carrier recombination dynamics in LWIR SL samples. Specifically we used temperature-dependent Hall effect and time-resolved pump-probe measurements to study the effect of adjusting several growth parameters on the background carrier concentrations and studied carrier lifetimes in LWIR SLs.

  6. Survey and discussion of models applicable to the transport and fate thrust area of the Department of Energy Chemical and Biological Nonproliferation Program

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-09-01

    The availability and easy production of toxic chemical and biological agents by domestic and international terrorists pose a serious threat to US national security, especially to civilian populations in and around urban areas. To address this threat, the Department of Energy (DOE) has established the Chemical and Biological Nonproliferation Program (CBNP) with the goal of focusing the DOE`s technical resources and expertise on capabilities to deny, deter, mitigate and respond to clandestine releases of chemical and biological agents. With the intent to build on DOE core competencies, the DOE has established six technology thrust areas within the CBNP Program: Biological Information Resources; Point Sensor Systems; Stand-off Detection; Transport and Fate; Decontamination; and Systems Analysis and Integration. The purpose of the Transport and Fate Thrust is to accurately predict the dispersion, concentration and ultimate fate of chemical and biological agents released into the urban and suburban environments and has two major goals: (1) to develop an integrated and validated state-of-the-art atmospheric transport and fate modeling capability for chemical and biological agent releases within the complex urban environment from the regional scale down to building and subway interiors, and (2) to apply this modeling capability in a broad range of simulation case studies of chemical and biological agent release scenarios in suburban, urban and confined (buildings and subways) environments and provide analysis for the incident response user community. Sections of this report discuss subway transport and fate models; buildings interior transport and fate modeling; models for flow and transport around buildings; and local-regional meteorology and dispersion models.

  7. Persistence of gamma-H2AX and 53BP1 foci in proliferating and nonproliferating human mammary epithelial cells after exposure to gamma-rays or iron ions

    Energy Technology Data Exchange (ETDEWEB)

    Groesser, Torsten; Chang, Hang; Fontenay, Gerald; Chen, James; Costes, Sylvain V.; Barcellos-Hoff, Mary Helen; Parvin, Bahram; Rydberg, Bjorn

    2010-12-22

    To investigate {gamma}-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionizing radiation under different cell culture conditions. HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure. Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced {gamma}-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both {gamma}-H2AX and 53BP1 foci decreased to control levels during the 24-48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after {gamma}-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition. Conclusions: The disappearance of radiation induced {gamma}-H2AX and 53BP1 foci in HMEC have different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent {gamma}-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodeling.

  8. Preliminary results of calculations for heavy-water nuclear-power-plant reactors employing 235U, 233U, and 232Th as a fuel and meeting requirements of a nonproliferation of nuclear weapons

    Science.gov (United States)

    Ioffe, B. L.; Kochurov, B. P.

    2012-02-01

    A physical design is developed for a gas-cooled heavy-water nuclear reactor intended for a project of a nuclear power plant. As a fuel, the reactor would employ thorium with a small admixture of enriched uranium that contains not more than 20% of 235U. It operates in the open-cycle mode involving 233U production from thorium and its subsequent burnup. The reactor meets the conditions of a nonproliferation of nuclear weapons: the content of fissionable isotopes in uranium at all stages of the process, including the final one, is below the threshold for constructing an atomic bomb, the amount of product plutonium being extremely small.

  9. Alloying InAs and InP nanowires for optoelectronic applications: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Toniolo, Giuliano R.; Anversa, Jonas [Departamento de Fisica, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil); Santos, Cláudia L. dos [Área de Ciências Tecnológicas, Centro Universitário Franciscano, 97010-032, Santa Maria, RS (Brazil); Piquini, Paulo, E-mail: paulo.piquini@ufsm.br [Departamento de Fisica, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil)

    2014-08-01

    The capability of nanowires to relieve the stress introduced by lattice mismatching through radial relaxation opens the possibility to search for devices for optoelectronic applications. However, there are difficulties to fabricate, and therefore to explore the properties of nanowires with narrow diameters. Here we apply first principles calculations to study the electronic and optical properties of narrow InAs{sub 1−x}P{sub x} nanowires. Our results show that the absorption threshold can be pushed to near-ultraviolet region, and suggests that arrays of these nanowires with different diameters and compositions could be used as devices acting from the mid-infrared to the near-ultraviolet region. - Highlights: • The optical properties of InAsP alloy nanowires were studied using DFT calculations. • The variation of band edges and band offsets with composition were determined. • The dependence of the optical absorption with alloy composition was settled. • The onset for optical absorption is suggested to be pushed to the UV region.

  10. Comparison between mini mental state examination (MMSE) and Montreal cognitive assessment Indonesian version (MoCA-Ina) as an early detection of cognitive impairments in post-stroke patients

    Science.gov (United States)

    Lestari, S.; Mistivani, I.; Rumende, C. M.; Kusumaningsih, W.

    2017-08-01

    Mild cognitive impairment (MCI) is defined as cognitive impairment that may never develop into dementia. Cognitive impairment is one long-term complication of a stroke. The Mini Mental State Examination (MMSE), which is commonly used as a screening tool for cognitive impairment, has a low sensitivity to detect cognitive impairment, especially MCI. Alternatively, the Montreal Cognitive Assessment Indonesian version (MoCA-Ina) has been reported to have a higher sensitivity than the MMSE. The aim of this study was to compare the proportion of MCI identified between the MMSE and MoCA-Ina in stroke patients. This was a cross-sectional study of stroke outpatients who attended the Polyclinic Neuromuscular Division, Rehabilitation Department, and Polyclinic Stroke, Neurology Department Cipto Mangunkusumo General Hospital, Jakarta. The proportion of MCI identified using the MMSE was 31.03% compared to 72.41% when using the MoCA-Ina. This difference was statistically significant (Fisher’s exact test, p = 0.033). The proportion of MCI in stroke patients was higher when using the MoCA-Ina compared to the MMSE. The MoCA-Ina should be used as an alternative in the early detection of MCI in stroke patients, especially those undergoing rehabilitation.

  11. Stress-determined nucleation sites above GaAs-capped arrays of InAs quantum dots

    Science.gov (United States)

    Latini, V.; Placidi, E.; Arciprete, F.; Tisbi, E.; Patella, F.; Magri, R.

    2016-09-01

    We studied the stress field at the surface of GaAs capping layers of variable thicknesses burying InAs quantum dot arrays using the Finite Element method to solve numerically the equations of the elastic field. The aim is to determine the stress-determined favorable sites for dot nucleation. We show that: (i) depending on the cap thickness, dot distances, and array orientation, sudden transitions in the stress-strain fields occur, leading from a vertical alignment of the dots to an anti-aligned correlation. We find that just few determined positions are favorable for dot nucleation and exclude some other sites previously indicated as favorable in the literature; (ii) the critical thicknesses at which the switch between the vertical alignment and the anti-aligned positions occurs depend on the distance between the dots in a square array and on the ratio between the two different distances if the arrays are rectangular; (iii) the transitions occur within a few nanometer range of the capping layer thickness, and the elastic field undergoes large changes in its properties before and after the transition. This behavior has been revealed by a very accurate fit of the tangential stress field using appropriate fit functions. The fit and parameter functions allow to easily reproduce the stress field in different contexts and are useful in growth simulation models. The results suggest that by properly engineering the capping layer thicknesses in the layers of a stack, it is possible to obtain different three-dimensional quantum dot lattices starting from an initial fixed dot array. Our results are in agreement with the available experimental data.

  12. Emission-wavelength tuning of InAs quantum dots grown on nitrogen-δ-doped GaAs(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kaizu, Toshiyuki, E-mail: kaizu@crystal.kobe-u.ac.jp [Center for Supports to Research and Education Activities, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan); Department of Electrical and Electronic Engineering, Faculty of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan); Taguchi, Kohei; Kita, Takashi [Department of Electrical and Electronic Engineering, Faculty of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)

    2016-05-21

    We studied the structural and photoluminescence (PL) characteristics of InAs quantum dots (QDs) grown on nitrogen (N) δ-doped GaAs(001). The emission wavelength for low-density N-δ doping exhibited a blueshift with respect to that for undoped GaAs and was redshifted with increasing N-sheet density. This behavior corresponded to the variation in the In composition of the QDs. N-δ doping has two opposite and competing effects on the incorporation of Ga atoms from the underlying layer into the QDs during the QD growth. One is the enhancement of Ga incorporation induced by the lattice strain, which is due to the smaller radius of N atoms. The other is an effect blocking for Ga incorporation, which is due to the large bonding energy of Ga-N or In-N. At a low N-sheet density, the lattice-strain effect was dominant, while the blocking effect became larger with increasing N-sheet density. Therefore, the incorporation of Ga from the underlying layer depended on the N-sheet density. Since the In-Ga intermixing between the QDs and the GaAs cap layer during capping also depended on the size of the as-grown QDs, which was affected by the N-sheet density, the superposition of these three factors determined the composition of the QDs. In addition, the piezoelectric effect, which was induced with increased accumulation of lattice strain and the associated high In composition, also affected the PL properties of the QDs. As a result, tuning of the emission wavelength from 1.12 to 1.26 μm was achieved at room temperature.

  13. Minimization of material inter-diffusion for thermally stable quaternary-capped InAs quantum dot via strain modification

    Science.gov (United States)

    Ghadi, Hemant; Sehara, Navneet; Murkute, Punam; Chakrabarti, Subhananda

    2017-05-01

    In this study, a theoretical model is developed for investigating the effect of thermal annealing on a single-layer quaternary-capped (In0.21Al0.21Ga0.58As) InAs quantum dot heterostructure (sample A) and compared to a conventional GaAs-capped sample (sample B). Strain, an interfacial property, aids in dot formation; however, it hinders interdiffusion (up to 650 °C), rendering thermal stability to heterostructures. Three diffusing species In/Al/Ga intermix because of the concentration gradient and temperature variation, which is modeled by Fick's law of diffusion. Ground-state energy for both carriers (electron and holes) is calculated by the Schrodinger equation at different annealing temperatures, incorporating strain computed by the concentration-dependent model. Change in activation energy due to strain decreases particle movement, thereby resulting in thermally stable structures at low annealing temperatures. At low temperature, the conduction band near the dot edge slightly decreases, attributed to the comparatively high strain. Calculated results are consistent with the experimental blue-shift i.e. towards lower wavelength of photoluminescence peak on the same sample with increasing annealing temperatures. Cross-sectional transmission microscopy (TEM) images substantiate the existence of dot till 800 °C for sample (A). With increasing annealing temperature, interdiffusion and dot sublimation are observed in XTEM images of samples A and B. Strain calculated from high-resolution X-ray diffraction (HRXRD) peaks and its decline with increasing temperature are in agreement with that calculated by the model. For highlighting the benefits of quaternary capping, InAlGaAs capping is theoretically and experimentally compared to GaAs capping. Concentration-dependent strain energy is calculated at every point and is further used for computing material interdiffusion, band profiles, and photoluminescence peak wavelength, which can provide better insights into strain

  14. Quantitative analysis of the interplay between InAs quantum dots and wetting layer during the GaAs capping process

    Science.gov (United States)

    González, D.; Braza, V.; Utrilla, A. D.; Gonzalo, A.; Reyes, D. F.; Ben, T.; Guzman, A.; Hierro, A.; Ulloa, J. M.

    2017-10-01

    A procedure to quantitatively analyse the relationship between the wetting layer (WL) and the quantum dots (QDs) as a whole in a statistical way is proposed. As we will show in the manuscript, it allows determining, not only the proportion of deposited InAs held in the WL, but also the average In content inside the QDs. First, the amount of InAs deposited is measured for calibration in three different WL structures without QDs by two methodologies: strain mappings in high-resolution transmission electron microscopy images and compositional mappings with ChemiSTEM x-ray energy spectrometry. The area under the average profiles obtained by both methodologies emerges as the best parameter to quantify the amount of InAs in the WL, in agreement with high-resolution x-ray diffraction results. Second, the effect of three different GaAs capping layer (CL) growth rates on the decomposition of the QDs is evaluated. The CL growth rate has a strong influence on the QD volume as well as the WL characteristics. Slower CL growth rates produce an In enrichment of the WL if compared to faster ones, together with a diminution of the QD height. In addition, assuming that the QD density does not change with the different CL growth rates, an estimation of the average In content inside the QDs is given. The high Ga/In intermixing during the decomposition of buried QDs does not only trigger a reduction of the QD height, but above all, a higher impoverishment of the In content inside the QDs, therefore modifying the two most important parameters that determine the optical properties of these structures.

  15. ANALYSIS OF INA-CBG’S FARE AND GOVERNOR REGULATION FAREON SURGERY AT INPATIENT ROOM OF UNDATA REGIONAL PUBLIC HOSPITAL IN PALU

    Directory of Open Access Journals (Sweden)

    Muh. Ryman Napirah

    2016-03-01

    Full Text Available Aim: In order to determine the fares of surgery, there are two types of fares used by hospitals namely Indonesian Case Based Groups fare (INA-CBG s and Governor Regulation fare. This study aimed to identify and analyze both types of fares in orthopedic surgery, general, eyes, midwifery, mouth, ENT, urology at inpatient room of Undata Regional Public Hospital in Palu during year 2014. Method: This was a quantitative study with descriptive approach with 46 cases as the number of surgery. Data were collected through observation and analysis of secondary data were gotten from medical record, pharmaceutical installation of IBS/IDR, inpatient therapy room (Matahari, Aster, and Teratai pavilions and cashier of inpatient room in form of cost details and patient data from January to December 2014. Data Presentation was formed on tables, where the existing fares are grouped based on the component of each cost then summed and calculated the deviation between the two types of fares. Results: This study indicated that orthopedic surgery with deviation of Rp 11.311.365, general surgery with deviation of Rp 6.438.409, eyes surgery with deviation of Rp 45.173.741, midwifery surgery with deviation of Rp 6.645.765, oral surgery with deviation of Rp 6.105.659, and urological surgery with deviation of Rp. 3.809.959. Conclusion: It can be concluded that INA-CBG's fares are higher than Governor Regulation fares except orthopedic surgery, where the Governor Regulation faresare higher than INA-CBG’s fares.

  16. Surface Chemistry and Interface Evolution during the Atomic Layer Deposition of High-k Metal Oxides on InAs(100) and GaAs(100) Surfaces

    Science.gov (United States)

    Henegar, Alex J.

    Device scaling has been key for creating faster and more powerful electronic devices. Integral circuit components like the metal-oxide semiconductor field-effect transistor (MOSFET) now rely on material deposition techniques, like atomic layer deposition (ALD), that possess atomic-scale thickness precision. At the heart of the archetypal MOSFET is a SiO2/Si interface which can be formed to near perfection. However when the thickness of the SiO 2 layer is shrunk down to a few nanometers several complications arise like unacceptably high leakage current and power consumption. Replacing Si with III-V semiconductors and SiO2 with high-k dielectric materials is appealing but comes with its own set of challenges. While SiO2 is practically defect-free, the native oxides of III-Vs are poor dielectrics. In this dissertation, the surface chemistry and interface evolution during the ALD of high-k metal oxides on Si(100), GaAs(100) and InAs(100) was studied. In particular, the surface chemistry and crystallization of TiO2 films grown on Si(100) was investigated using transmission Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Large, stable, and highly reactive anatase TiO2 grains were found to form during a post-deposition heat treatment after the ALD at 100 °C. The remainder of this work was focused on the evolution of the interfacial oxides during the deposition of TiO2 and Al2O3 on InAs(100) and GaAs(100) and during the deposition of Ta2O 5 on InAs(100). In summary the ALD precursor type, deposited film, and substrate had an influence in the evolution of the native oxides. Alkyl amine precursors fared better at removing the native oxides but the deposited films (TiO2 and Ta2O5) were susceptible to significant native oxide diffusion. The alkyl precursor used for the growth of Al 2O3 was relatively ineffective at removing the oxides but was

  17. Electrical spin injection in InAs quantum dots at room temperature and adjustment of the emission wavelength for spintronic applications

    Science.gov (United States)

    Ludwig, A.; Roescu, R.; Rai, A. K.; Trunov, K.; Stromberg, F.; Li, M.; Soldat, H.; Ebbing, A.; Gerhardt, N. C.; Hofmann, M. R.; Wende, H.; Keune, W.; Reuter, D.; Wieck, A. D.

    2011-05-01

    We have observed room temperature (RT) electrical spin injection in an InAs quantum dot (QD) light emitting diode (LED) grown on a p-type GaAs substrate from a ferromagnetic Fe/Tb electrode with strong out-of-plane anisotropy in remanence, i.e. without applied magnetic field. The QDs in the LED emit at 1275 nm (ground state luminescence), which is beyond the range for highly sensitive detectors, and therefore not optimum for various applications, e.g. quantum information studies. We will present two different ways to blue-shift the emission wavelength and discuss the advantages and drawbacks of the experiments.

  18. Arsenic-induced intensity oscillations in reflection high-energy electron diffraction measurements. [during MBE of GaAs and InAs

    Science.gov (United States)

    Lewis, B. F.; Fernandez, R.; Grunthaner, F. J.; Madhukar, A.

    1986-01-01

    A technique of arsenic-induced RHEED intensity oscillations has been used to accurately measure arsenic incorporation rates as a function of substrate temperature during the homoepitaxial growths of both GaAs and InAs by molecular beam epitaxy (MBE). Measurements were made at growth temperatures from 350 to 650 C and at arsenic fluxes of 0.1 to 10.0 monolayer/s. The method measures only the arsenic actually incorporated into the growing film and does not include the arsenic lost in splitting the arsenic tetramers or lost by evaporation from the sample.

  19. The Influence of Ultrasound on the Energy Spectrum of Electron and Holein InAs/GaAs Heterosystem with InAs Quantum Dots

    Directory of Open Access Journals (Sweden)

    R.M. Peleshchak

    2016-12-01

    Full Text Available On the basis of the method of electron-deformation relation and perturbation theory the model of heterostructure with spherical quantum dots which is exposed to ultrasound is developed. Within this model it is investigated the influence of the acoustic wave on the ground state energy of electron and hole, the band gap energy and energy of recombination radiation of InAs/GaAs heterostructure with InAs spherical quantum dots. The offered model considers the distortion of the form of quantum dot and its volume change under the influence of the acoustic wave.

  20. Large array of single, site-controlled InAs quantum dots fabricated by UV-nanoimprint lithography and molecular beam epitaxy.

    Science.gov (United States)

    Schramm, A; Tommila, J; Strelow, C; Hakkarainen, T V; Tukiainen, A; Dumitrescu, M; Mews, A; Kipp, T; Guina, M

    2012-05-04

    We present the growth of single, site-controlled InAs quantum dots on GaAs templates using UV-nanoimprint lithography and molecular beam epitaxy. A large quantum dot array with a period of 1.5 µm was achieved. Single quantum dots were studied by steady-state and time-resolved micro-photoluminescence experiments. We obtained single exciton emission with a linewidth of 45 µeV. In time-resolved experiments, we observed decay times of about 670 ps. Our results underline the potential of nanoimprint lithography and molecular beam epitaxy to create large-scale, single quantum dot arrays.

  1. Photoreflectance study of InAs ultrathin layer embedded in Si-delta-doped GaAs/AlGaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Dhifallah, I., E-mail: ines.dhifallah@gmail.co [Laboratoire de Photovoltaique, des Semiconducteurs et des Nanostructures, Centre de Recherche et des Technologies de l' energie, BP 95 Hammam-Lif 2050 (Tunisia); Daoudi, M.; Bardaoui, A. [Laboratoire de Photovoltaique, des Semiconducteurs et des Nanostructures, Centre de Recherche et des Technologies de l' energie, BP 95 Hammam-Lif 2050 (Tunisia); Eljani, B. [Unite de recherche sur les Hetero-Epitaxie et Applications, Faculte des Sciences de Monastir (Tunisia); Ouerghi, A. [Laboratoire de Photonique et de Nanostructures, CNRS Route de Nozay 91 46a0, Marcoussis (France); Chtourou, R. [Laboratoire de Photovoltaique, des Semiconducteurs et des Nanostructures, Centre de Recherche et des Technologies de l' energie, BP 95 Hammam-Lif 2050 (Tunisia)

    2011-05-15

    Photoreflectance and photoluminescence studies were performed to characterize InAs ultrathin layer embedded in Si-delta-doped GaAs/AlGaAs high electron mobility transistors. These structures were grown by Molecular Beam Epitaxy on (1 0 0) oriented GaAs substrates with different silicon-delta-doped layer densities. Interband energy transitions in the InAs ultrathin layer quantum well were observed below the GaAs band gap in the photoreflectance spectra, and assigned to electron-heavy-hole (E{sub e-hh}) and electron-light-hole (E{sub e-lh}) fundamental transitions. These transitions were shifted to lower energy with increasing silicon-{delta}-doping density. This effect is in good agreement with our theoretical results based on a self-consistent solution of the coupled Schroedinger and Poisson equations and was explained by increased escape of photogenerated carriers and enhanced Quantum Confined Stark Effect in the Si-delta-doped InAs/GaAs QW. In the photoreflectance spectra, not only the channel well interband energy transitions were observed, but also features associated with the GaAs and AlGaAs bulk layers located at about 1.427 and 1.8 eV, respectively. By analyzing the Franz-Keldysh Oscillations observed in the spectral characteristics of Si-{delta}-doped samples, we have determined the internal electric field introduced by ionized Si-{delta}-doped centers. We have observed an increase in the electric field in the InAs ultrathin layer with increasing silicon content. The results are explained in terms of doping dependent ionized impurities densities and surface charges. - Research highlights: {yields} Studying HEMTs structures with different silicon doping content. {yields} An increase of the electric field in the InAs layer with increasing Si content. {yields} The interband energy transitions in the HEMTs structures have been obtained from PR. {yields} Experimental and theoretical values of transitions energies were in good agreement.

  2. Current developments in laser ablation-inductively coupled plasma-mass spectrometry for use in geology, forensics, and nuclear nonproliferation research

    Energy Technology Data Exchange (ETDEWEB)

    Messerly, Joshua D. [Iowa State Univ., Ames, IA (United States)

    2008-08-26

    This dissertation focused on new applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The diverse fields that were investigated show the versatility of the technique. In Chapter 2, LA-ICP-MS was used to investigate the rare earth element (REE) profiles of garnets from the Broken Hill Deposit in New South Wales, Australia. The normalized REE profiles helped to shed new light on the formation of deposits of sulfide ores. This information may be helpful in identifying the location of sulfide ore deposits in other locations. New sources of metals such as Pg, Zn, and Ag, produced from these ores, are needed to sustain our current technological society. The application of LA-ICP-MS presented in Chapter 3 is the forensics analysis of automotive putty and caulking. The elemental analysis of these materials was combined with the use of Principal Components Analysis (PCA). The PCA comparison was able to differentiate the automotive putty samples by manufacturer and lot number. The analysis of caulk was able to show a differentiation based on manufacturer, but no clear differentiation was shown by lot number. This differentiation may allow matching of evidence in the future. This will require many more analyses and the construction of a database made up of many different samples. The 4th chapter was a study of the capabilities of LA-ICP-MS for fast and precise analysis of particle ensembles for nuclear nonproliferation applications. Laser ablation has the ability to spatially resolve particle ensembles which may contain uranium or other actinides from other particles present in a sample. This is of importance in samples obtained from air on filter media. The particle ensembles of interest may be mixed in amongst dust and other particulates. A problem arises when ablating these particle ensembles directly from the filter media. Dust particles other than ones of interest may be accidentally entrained in the aerosol of the ablated particle

  3. Reviewing the Nuclear Nonproliferation Treaty

    Science.gov (United States)

    2010-05-01

    several examples. At a fuel fabrication plant at Tokai-mura in Japan making mixed-oxide ( MOX ) fuel out of powdered uranium and nuclear weapons... MOX scrap in Japan where at least one bomb’s worth of weapons-usable plutonium went missing and another accounting discrepancy at a Japanese repro...mixed oxide fuels or MOX ) do not fare as well. Here, Dr. Cochran points out that it would take no more than a week and possibly as little as a few

  4. Ankyrin-G participates in INa remodeling in myocytes from the border zones of infarcted canine heart.

    Directory of Open Access Journals (Sweden)

    Wen Dun

    Full Text Available Cardiac Na channel remodeling provides a critical substrate for generation of reentrant arrhythmias in border zones of the infarcted canine heart. Recent studies show that Nav1.5 assembly and function are linked to ankyrin-G, gap, and mechanical junction proteins. In this study our objective is to expound the status of the cardiac Na channel, its interacting protein ankyrinG and the mechanical and gap junction proteins at two different times post infarction when arrhythmias are known to occur; that is, 48 hr and 5 day post coronary occlusion. Previous studies have shown the origins of arrhythmic events come from the subendocardial Purkinje and epicardial border zone. Our Purkinje cell (Pcell voltage clamp study shows that INa and its kinetic parameters do not differ between Pcells from the subendocardium of the 48hr infarcted heart (IZPCs and control non-infarcted Pcells (NZPCs. Immunostaining studies revealed that disturbances of Nav1.5 protein location with ankyrin-G are modest in 48 hr IZPCs. Therefore, Na current remodeling does not contribute to the abnormal conduction in the subendocardial border zone 48 hr post myocardial infarction as previously defined. In addition, immunohistochemical data show that Cx40/Cx43 co-localize at the intercalated disc (IDs of control NZPCs but separate in IZPCs. At the same time, Purkinje cell desmoplakin and desmoglein2 immunostaining become diffuse while plakophilin2 and plakoglobin increase in abundance at IDs. In the epicardial border zone 5 days post myocardial infarction, immunoblot and immunocytochemical analyses showed that ankyrin-G protein expression is increased and re-localized to submembrane cell regions at a time when Nav1.5 function is decreased. Thus, Nav1.5 and ankyrin-G remodeling occur later after myocardial infarction compared to that of gap and mechanical junctional proteins. Gap and mechanical junctional proteins remodel in IZPCs early, perhaps to help maintain Nav1.5 subcellular

  5. Nano- and picosecond 3 μm Er: YSGG lasers using InAs as passive Q-switchers and mode-lockers

    Science.gov (United States)

    Vodopyanov, K. L.; Lukashev, A. V.; Phillips, C. C.

    1993-01-01

    Recent results are reported using ultra-thin molecular beam epitaxy (MBE)-grown InAs epilayers on GaAs substrates as passive shutters for 3 μm Er: YSGG lasers ( λ = 2.8 μm). The laser photon energy is 27% higher than the InAs bandgap at 300 K and bleaching occurs due to a band filling effect with a fast recovery time of < 100 ps. Depending on the resonator geometry two modes of operation can be achieved: Q-switched with pulse duration of 35 ns and 5-6 mJ energy (TEM 00 mode) and a Q-switched/mode-locked regime with an output in the form of a train of 30 pulses separated by a 4.3 ns interval, 0.25 mJ energy per spike and 30-50 ps pulse duration in a TEM 00-mode. The latter are the shortest pulses obtained with this lasing medium to date.

  6. Studies on the controlled growth of InAs nanostructures on scission surfaces; Untersuchungen zum kontrollierten Wachstum von InAs-Nanostrukturen auf Spaltflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, J.

    2006-01-15

    The aim of this thesis was the controlled alignment of self-assembled InAs nano-structures on a {l_brace}110{r_brace}-oriented surface. The surface is prestructured with the atomic precision offered by molecular beam epitaxy, using the cleaved edge overgrowth-technique. On all samples grown within this work, the epitaxial template in the first growth step was deposited on a (001)GaAs substrate, while the InAs-layer forming the nanostructures during the second growth step was grown on cleaved {l_brace}110{r_brace}-GaAs surfaces. Atomic Force Microscopy (AFM) investigations demonstrate the formation of quantum dot (QD)-like nanostructures on top of the AlAs-stripes. X-ray diffraction measurements on large arrays of aligned quantum dots demonstrate that the quantum dots are formed of pure InAs. First investigations on the optical properties of these nanostructures were done using microphotoluminescence-spectroscopy with both high spatial and spectral resolution. (orig.)

  7. Optical and electronic study on InAs quantum dots doped with rare earths; Optische und elektronische Untersuchung an mit Seltenen Erden dotierten InAs-Quantenpunkten

    Energy Technology Data Exchange (ETDEWEB)

    Greff, Markus Karlheinz

    2015-07-01

    In the framework of this thesis it was studied, how the optical and electronic properties of InAs quantum dots change by the implantation of ions form the group of the rare earths. For this photoluminescence measurements as well as C(V) measurements were performed on InAs quantum dots, which were doped with europium as well as erbium. The optical studies showed a new emission peak in the photoluminescence spectrum after the thermal annealing. By the ions brought in by means of ion implantation it came locally to lattice stresses and an accumulation of lattice defects on the interfaces of the quantum dots, which led to a diffusion strengthening, whereby it came during the thermal annealing both to a broadening of the quantum dots by the indium diffusion and to an increasement of the band gap by gallium diffusion into the quantum dot. Thereby a shift of the ground-state energy of up to 150 meV could be measured.

  8. Superluminescent diode with a broadband gain based on self-assembled InAs quantum dots and segmented contacts for an optical coherence tomography light source

    Science.gov (United States)

    Ozaki, Nobuhiko; Childs, David T. D.; Sarma, Jayanta; Roberts, Timothy S.; Yasuda, Takuma; Shibata, Hiroshi; Ohsato, Hirotaka; Watanabe, Eiichiro; Ikeda, Naoki; Sugimoto, Yoshimasa; Hogg, Richard A.

    2016-02-01

    We report a broadband-gain superluminescent diode (SLD) based on self-assembled InAs quantum dots (QDs) for application in a high-resolution optical coherence tomography (OCT) light source. Four InAs QD layers, with sequentially shifted emission wavelengths achieved by varying the thickness of the In0.2Ga0.8As strain-reducing capping layers, were embedded in a conventional p-n heterojunction comprising GaAs and AlGaAs layers. A ridge-type waveguide with segmented contacts was formed on the grown wafer, and an as-cleaved 4-mm-long chip (QD-SLD) was prepared. The segmented contacts were effective in applying a high injection current density to the QDs and obtaining emission from excited states of the QDs, resulting in an extension of the bandwidth of the electroluminescence spectrum. In addition, gain spectra deduced with the segmented contacts indicated a broadband smooth positive gain region spanning 160 nm. Furthermore, OCT imaging with the fabricated QD-SLD was performed, and OCT images with an axial resolution of ˜4 μm in air were obtained. These results demonstrate the effectiveness of the QD-SLD with segmented contacts as a high-resolution OCT light source.

  9. GaAs metal-oxide-semiconductor based non-volatile flash memory devices with InAs quantum dots as charge storage nodes

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Sk Masiul, E-mail: masiulelt@gmail.com; Chowdhury, Sisir; Sarkar, Krishnendu; Nagabhushan, B.; Banerji, P. [Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302 (India); Chakraborty, S. [Applied Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Sector-I, Kolkata 700 064 (India); Mukherjee, Rabibrata [Department of Chemical Engineering, Indian Institute of Technology, Kharagpur 721302 (India)

    2015-06-24

    Ultra-thin InP passivated GaAs metal-oxide-semiconductor based non-volatile flash memory devices were fabricated using InAs quantum dots (QDs) as charge storing elements by metal organic chemical vapor deposition technique to study the efficacy of the QDs as charge storage elements. The grown QDs were embedded between two high-k dielectric such as HfO{sub 2} and ZrO{sub 2}, which were used for tunneling and control oxide layers, respectively. The size and density of the QDs were found to be 5 nm and 1.8×10{sup 11} cm{sup −2}, respectively. The device with a structure Metal/ZrO{sub 2}/InAs QDs/HfO{sub 2}/GaAs/Metal shows maximum memory window equivalent to 6.87 V. The device also exhibits low leakage current density of the order of 10{sup −6} A/cm{sup 2} and reasonably good charge retention characteristics. The low value of leakage current in the fabricated memory device is attributed to the Coulomb blockade effect influenced by quantum confinement as well as reduction of interface trap states by ultra-thin InP passivation on GaAs prior to HfO{sub 2} deposition.

  10. Diffusion and interface evolution during the atomic layer deposition of TiO{sub 2} on GaAs(100) and InAs(100) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Liwang; Gougousi, Theodosia, E-mail: gougousi@umbc.edu [Department of Physics, UMBC, Baltimore, Maryland 21250 (United States)

    2016-01-15

    Atomic layer deposition is used to form TiO{sub 2} films from tetrakis dimethyl amino titanium and H{sub 2}O on native oxide GaAs(100) and InAs(100) surfaces. The evolution of the film/substrate interface is examined as a function of the deposition temperature (100–325 °C) using ex situ x-ray photoelectron spectroscopy. An increase in the deposition temperature up to 250 °C leads to enhancement of the native oxide removal. For depositions at 300 °C and above, interface reoxidation is observed during the initial deposition cycles but when the films are thicker than 3 nm, the surface oxides are removed steadily. Based on these observations, two distinct film growth regimes are identified; up to 250 °C, layer-by-layer dominates while at higher temperatures island growth takes over. Angle resolved x-ray photoelectron spectroscopy measurements performed on 3 nm TiO{sub 2} film deposited at 325 °C on both surfaces demonstrates a very important difference between the two substrates: for GaAs the native oxides remaining in the stack are localized at the interface, while for InAs(100), the indium oxides are mixed in the TiO{sub 2} film.

  11. Analysis by high-resolution electron microscopy of elastic strain in thick InAs layers embedded in Ga{sub 0.47}In{sub 0.53}As buffers on InP(0 0 1) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Gatel, C., E-mail: gatel@cemes.fr [CNRS, CEMES (Centre d' Elaboration des Materiaux et d' Etudes Structurales), BP 94347, 29 rue J. Marvig, 31055 Toulouse (France)] [Universite de Toulouse, UPS, 31055 Toulouse (France); Tang, H.; Crestou, C.; Ponchet, A. [CNRS, CEMES (Centre d' Elaboration des Materiaux et d' Etudes Structurales), BP 94347, 29 rue J. Marvig, 31055 Toulouse (France)] [Universite de Toulouse, UPS, 31055 Toulouse (France); Bertru, N.; Dore, F.; Folliot, H. [FOTON-LENS-INSA, 20 av. des Buttes de Coesmes, CS 14315, 35043 Rennes (France)

    2010-05-15

    Elastic strain has been investigated by transmission electron microscopy in nanometric InAs layers grown on Ga{sub 0.47}In{sub 0.53}As/InP(0 0 1) by molecular beam epitaxy using a residual Sb flux. Deposits of 10 and 15 monolayers of InAs (3 and 4.5 nm) remain elastically stressed with a two-dimensional growth mode. The out-of-plane strain in the layers is analyzed by cross-sectional high-resolution electron microscopy. A distortion of the substrate below and on top of the InAs layers is detected and is attributed to a significant surface relaxation effect due to thinning. Surface relaxation is modeled by three-dimensional finite element modeling. An additional relaxation effect is obtained when the sample is not infinite along the direction perpendicular to the thinning. This effect enhances the buffer distortion of the buffers below and on top of the strained layers. Taking into account thin foil effects, the experimental out-of-plane strain is in excellent agreement with the theoretical value calculated for a pure InAs layer (i.e. 0.035), demonstrating the high level of strain and stress in the layers.

  12. Autism: Why Act Early?

    Science.gov (United States)

    ... What's this? Submit Button Past Emails CDC Features Autism: Why Act Early? Language: English Español (Spanish) Recommend ... helped the world make sense." Florida teenager with Autism Spectrum Disorder "Because my parents acted early, I ...

  13. The dermatology acting internship.

    Science.gov (United States)

    Stephens, John B; Raimer, Sharon S; Wagner, Richard F

    2011-07-15

    Acting internships are an important component of modern day medical school curriculum. Several specialties outside of internal medicine now offer acting internship experiences to fourth year medical students. We have found that a dermatology acting internship is a valuable experience for fourth year medical students who are interested in pursuing a residency in dermatology. Our experience with the dermatology acting internship over the 2010-2011 academic year is described.

  14. The Non-Proliferation Treaty of Nuclear Weapons (NPT) and the insertion of the Brazilian State in its regime; O tratado sobre a nao proliferacao de armas nucleares (TNP) e a insercao do Estado brasileiro no regime dele decorrente

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcos Valle Machado da

    2010-07-01

    The issue of nuclear weapons continues to appear as a focal point of International Relations. The efforts and concrete actions on disarmament, non-proliferation, and nuclear arms control are still issues that generate recurring tensions between States. However, in Brazil, there is little analysis of an academic nature about these issues and, with respect to current and prospective position of the Brazilian State in the Nuclear Weapons Non- Proliferation Regime, studies and analysis are even more scarce, or incipient. The present dissertation has as its object of study to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the Regime arisen from NPT, and the Brazilian State insertion process in this Regime. Therefore our research work is structured in three areas: the first one is about the role of nuclear weapons in States security perception, the second is about NPT and its Regime, the third runs over the insertion of the Brazilian state in this regime. So, in summary, the research performed included the reasons that make a State to develop nuclear weapons, the NPT genesis and evolution of the perception of the meaning of that Treaty by the States, and the process and the degree of insertion of Brazil in the Nuclear Weapons Non- Proliferation Regime. The inquiry sought to place this object of study in the broader debate on Foreign Relations, based on the approaches of the discipline devoted to the question of managing the security of States, id est, the two approaches that constitute the mainstream of the discipline: the perspective theoretical liberal (and neoliberal variants) and realistic thinking (and neo-realist). Thus, we have used different theoretical lenses, which we think necessary for understanding the specific parts and causal connections between these parts of a complex issue. (author)

  15. Identificação do vírus causador de encefalomielite eqüina, Paraná, Brasil

    Directory of Open Access Journals (Sweden)

    Fernández Zoraida

    2000-01-01

    Full Text Available OBJETIVO: No período de 1996 a 1999, um agente viral causador de encefalomielite afetou as populações de eqüinos em diferentes regiões do Estado do Paraná, Brasil. Objetivou-se realizar pesquisa sorológica na tentativa de isolar o vírus causador da doença. MÉTODOS: Em quatro municípios do Estado do Paraná, Brasil, foram coletados culicídeos com armadilha Shannon e isca humana, identificados e processados para isolamento de vírus. Em dois municípios estudados foram colhidas amostras de sangue de eqüinos para isolamento de vírus e para pesquisa sorológica. Os soros foram analisados pelo teste de inibição da hemaglutinação frente a diferentes antígenos de Alphavirus e Flavivirus. Aqueles que revelaram reações positivas-cruzadas foram analisados pelo teste de neutralização. RESULTADOS: Foram coletados culicídeos dos gêneros: Culex, Aedes, Mansonia, Coquillettidia, Psorophora, Sabethes, Wyeomyia e Limatus. Embora não sendo isolado o agente viral, foram detectados anticorpos hemaglutinantes para os vírus Encefalomielite eqüina do Leste, Mucambo, Pixuna, Maguari e St. Luis. Em doze amostras de soros foram detectados anticorpos neutralizantes para os vírus Encefalomielite eqüina do Leste. CONCLUSÕES: Foram coletadas espécies de culicídeos, considerados na bibliografia como vetores de vírus causadores de encefaliomielite buniavírus e outras arboviroses de importância epidemiológica. Pela presença de sintomas de encefalomielite e de anticorpos para o vírus Encefalomielite eqüina do Leste nos soros dos cavalos, supõe-se ser esse o vírus causador da doença nos eqüinos das regiões estudadas.

  16. Identificação do vírus causador de encefalomielite eqüina, Paraná, Brasil

    Directory of Open Access Journals (Sweden)

    Zoraida Fernández

    2000-06-01

    Full Text Available OBJETIVO: No período de 1996 a 1999, um agente viral causador de encefalomielite afetou as populações de eqüinos em diferentes regiões do Estado do Paraná, Brasil. Objetivou-se realizar pesquisa sorológica na tentativa de isolar o vírus causador da doença. MÉTODOS: Em quatro municípios do Estado do Paraná, Brasil, foram coletados culicídeos com armadilha Shannon e isca humana, identificados e processados para isolamento de vírus. Em dois municípios estudados foram colhidas amostras de sangue de eqüinos para isolamento de vírus e para pesquisa sorológica. Os soros foram analisados pelo teste de inibição da hemaglutinação frente a diferentes antígenos de Alphavirus e Flavivirus. Aqueles que revelaram reações positivas-cruzadas foram analisados pelo teste de neutralização. RESULTADOS: Foram coletados culicídeos dos gêneros: Culex, Aedes, Mansonia, Coquillettidia, Psorophora, Sabethes, Wyeomyia e Limatus. Embora não sendo isolado o agente viral, foram detectados anticorpos hemaglutinantes para os vírus Encefalomielite eqüina do Leste, Mucambo, Pixuna, Maguari e St. Luis. Em doze amostras de soros foram detectados anticorpos neutralizantes para os vírus Encefalomielite eqüina do Leste. CONCLUSÕES: Foram coletadas espécies de culicídeos, considerados na bibliografia como vetores de vírus causadores de encefaliomielite buniavírus e outras arboviroses de importância epidemiológica. Pela presença de sintomas de encefalomielite e de anticorpos para o vírus Encefalomielite eqüina do Leste nos soros dos cavalos, supõe-se ser esse o vírus causador da doença nos eqüinos das regiões estudadas.

  17. Structural and optical characterization of InAs/GaSb type-II superlattices: Influence of the change in InAs and GaSb layer thicknesses for fixed InSb-like interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Arikan, Bulent, E-mail: bulentarikanx@gmail.com; Korkmaz, Melih; Aslan, Bulent; Serincan, Uğur

    2015-08-31

    In this article, we report on the molecular beam epitaxy growth and characterization of a 140 period InAs/GaSb type-II superlattice structure designed for mid infrared detection. Thickness of a period was systematically altered in each sample by changing the thickness of InAs (GaSb) layers from 9 to 7 monolayers (ML) for a fixed GaSb (InAs) layer at 9 ML (7 ML). The same InSb-like strain compensation interface was used for all samples. High resolution X-ray diffraction analysis, spectral responsivity and external quantum efficiency (QE) measurements were performed to express the effects of layer thickness variations on both structural and photodetector features. The decrease in the InAs thickness resulted in the increased mismatch from 0 to + 1626 ppm and the blue shift in the 50% cut-off wavelength (λ{sub c}) from 5.41 to 4.36 μm at 77 K. The additional decrease in GaSb thickness caused further increase in the mismatch up to + 1791 ppm. The steepness of the photoresponse at the absorption band edge was quantified and presented comparatively with different photodetector parameters and material properties for a complete picture. The highest optical response was obtained from sample having 8 ML InAs and 9 ML GaSb with λ{sub c} = 4.76 μm and QE = 23.7% at 4 μm. - Highlights: • Detailed growth conditions for InAs/GaSb SLs designed for infrared detection • Precisely engineering the λ{sub c} and the ∆a{sub ⊥}/a by controlling the SL layer thicknesses • InAs layer thickness changes are more effective than the GaSb on the λ{sub c} and ∆a{sub ⊥}/a.

  18. Effects of InAlAs strain reducing layer on the photoluminescence properties of InAs quantum dots embedded in InGaAs/GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lingmin, E-mail: konglm@qq.com [School of Marine Science and Technology, Zhejiang Ocean University, Zhoushan 316000 (China); Sun, Wei [SEM School of Electromechanical Engineering, Weifang Engineering Vocational College, Qingzhou 262500 (China); Feng, Zhe Chuan, E-mail: zcfeng@nut.edu.tw [Institute of Photonics and Optoelectronics, Department of Electrical Engineering, and Center for Emerging Material and Advanced Devices, National Taiwan University, Taipei 106-17, Taiwan (China); Xie, Sheng [School of Electronic and Information Engineering, Tianjin University, Tianjin 300072 (China); Zhou, Yunqing; Wang, Rui; Zhang, Cunxi; Zong, Zhaocun; Wang, Hongxia; Qiao, Qian [Department of Physics, Zhejiang Ocean University, Zhoushan 316000 (China); Wu, Zhengyun [Department of Physics, Xiamen University, Xiamen 361005 China (China)

    2014-07-01

    Two kinds of self-assembled quantum dots (QDs) embedded within InGaAs/GaAs quantum wells were grown by molecular beam epitaxy: one was capped with an InAlAs strain reducing (SR) layer, while the other was not. Their emission dynamics was investigated by time-resolved and temperature dependent (TD) photoluminescence (PL) measurements. A significant redshift can be observed in the emission peak position of InAs QDs with thin InAlAs SR cap layer, which results from SR effects. Different behaviors of the integrated PL intensity for the samples with or without InAlAs layer may be ascribed to the reduced carrier transition at higher temperature for the higher energy barrier of the InAlAs layer, and the TD mode of carrier migration. The PL decay time of quantum dots grown with InAlAs layer was much longer than that without the layer, which implies that the InAlAs layer with higher energy barrier may enhance the quantum restriction of carriers in InAs QDs. These observations are discussed from the viewpoint of strain compensation and potential barrier variation with SR layers. Our experiments also demonstrate that the main mode of carrier migration is quantum tunneling effect at lower temperature, while it is quantum transition at higher temperature. The results demonstrate the importance of InAlAs SR layer for the optical quality of InAs QDs. - Highlights: • InAs quantum dots (QDs) were grown on GaAs. • A thin InAlAs layer was grown on InAs QDs. • Temperature dependent photoluminescence (PL) and time-resolved PL were carried out. • Both a redshift and a double exponential decay of PL emission were generated by the InAlAs layer.

  19. Indirect Speech Acts

    Institute of Scientific and Technical Information of China (English)

    李威

    2001-01-01

    Indirect speech acts are frequently used in verbal communication, the interpretation of them is of great importance in order to meet the demands of the development of students' communicative competence. This paper, therefore, intends to present Searle' s indirect speech acts and explore the way how indirect speech acts are interpreted in accordance with two influential theories. It consists of four parts. Part one gives a general introduction to the notion of speech acts theory. Part two makes an elaboration upon the conception of indirect speech act theory proposed by Searle and his supplement and development of illocutionary acts. Part three deals with the interpretation of indirect speech acts. Part four draws implication from the previous study and also serves as the conclusion of the dissertation.

  20. Gate-induced transition between metal-type and thermally activated transport in self-catalyzed MBE-grown InAs nanowires.

    Science.gov (United States)

    Blömers, C; Rieger, T; Grap, T; Raux, M; Lepsa, M I; Lüth, H; Grützmacher, D; Schäpers, Th

    2013-08-16

    Electronic transport properties of InAs nanowires are studied systematically. The nanowires are grown by molecular beam epitaxy on a SiOx-covered GaAs wafer, without using foreign catalyst particles. Room-temperature measurements revealed relatively high resistivity and low carrier concentration values, which correlate with the low background doping obtained by our growth method. Transport parameters, such as resistivity, mobility, and carrier concentration, show a relatively large spread that is attributed to variations in surface conditions. For some nanowires the conductivity has a metal-type dependence on temperature, i.e. decreasing with decreasing temperature, while other nanowires show the opposite temperature behavior, i.e. temperature-activated characteristics. An applied gate voltage in a field-effect transistor configuration can switch between the two types of behavior. The effect is explained by the presence of barriers formed by potential fluctuations.

  1. Observation of Rabi Splitting from Surface-plasmon Coupled Conduction-state Transitions in Electrically-excited InAs Quantum Dots

    Energy Technology Data Exchange (ETDEWEB)

    Passmore, Brian S.; Adams, David C.; Ribaudo, Troy; Wasserman, Daniel; Lyon, Stephen; Chow, Weng W.; Shaner, Eric A.

    2011-02-09

    We demonstrate strong coupling between a surface plasmon and intersublevel transitions in self-assembled InAs quantum dots. The surface plasmon mode exists at the interface between the semiconductor emitter structure and a periodic array of holes perforating a metallic Pd/Ge/Au film that also serves as the top electrical contact for the emitters. Spectrally narrowed quantum-dot electroluminescence was observed for devices with varying subwavelength hole spacing. Devices designed for 9, 10, and 11 μm wavelength emission also exhibit a significant spectral splitting. The association of the splitting with quantum-dot Rabi oscillation is consistent with results from a calculation of spontaneous emission from an interacting plasmonic field and quantum-dot ensemble. The fact that this Rabi oscillation can be observed in an incoherently excited, highly inhomogeneously broadened system demonstrates the utility of intersublevel transitions in quantum dots for investigations of coherent transient and quantum coherence phenomena.

  2. Terahertz tunable detection in self-switching diodes based on high mobility semiconductors: InGaAs, InAs and InSb

    Energy Technology Data Exchange (ETDEWEB)

    Iniguez-de-la-Torre, I; Rodilla, H; Mateos, J; Pardo, D; Gonzalez, T [Departamento de Fisica Aplicada, Universidad de Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Song, A M, E-mail: indy@usal.e [School of Electrical and Electronic Engineering, University of Manchester, Manchester M60 1QD (United Kingdom)

    2009-11-15

    In this work we report on the use of high mobility materials in the channel of self-switching diodes as potential candidates for terahertz operation. By means of Monte Carlo simulations we envisage the feasibility of tuneable-by-geometry detection in the terahertz range. The low effective mass of InAs and InSb in relation to InGaAs enhances ballistic transport inside the diode, thus improving the amplitude and quality factor of the resonance found in the detection spectra of self-switching diodes. The frequency of the resonant peak is also increased with the use of these narrow band gap semiconductors. The analysis of the noise spectra provides useful information about the origin of the resonance. By decreasing temperature below 300 K, a clear improvement in detection sensitivity is also achieved.

  3. Telecommunication Wavelength-Band Single-Photon Emission from Single Large InAs Quantum Dots Nucleated on Low-Density Seed Quantum Dots

    Science.gov (United States)

    Chen, Ze-Sheng; Ma, Ben; Shang, Xiang-Jun; He, Yu; Zhang, Li-Chun; Ni, Hai-Qiao; Wang, Jin-Liang; Niu, Zhi-Chuan

    2016-08-01

    Single-photon emission in the telecommunication wavelength band is realized with self-assembled strain-coupled bilayer InAs quantum dots (QDs) embedded in a planar microcavity on GaAs substrate. Low-density large QDs in the upper layer active for ~1.3 μm emission are fabricated by precisely controlling the indium deposition amount and applying a gradient indium flux in both QD layers. Time-resolved photoluminescence (PL) intensity suggested that the radiative lifetime of their exciton emission is 1.5~1.6 ns. The second-order correlation function of g 2(0) < 0.5 which demonstrates a pure single-photon emission.

  4. Telecommunication Wavelength-Band Single-Photon Emission from Single Large InAs Quantum Dots Nucleated on Low-Density Seed Quantum Dots.

    Science.gov (United States)

    Chen, Ze-Sheng; Ma, Ben; Shang, Xiang-Jun; He, Yu; Zhang, Li-Chun; Ni, Hai-Qiao; Wang, Jin-Liang; Niu, Zhi-Chuan

    2016-12-01

    Single-photon emission in the telecommunication wavelength band is realized with self-assembled strain-coupled bilayer InAs quantum dots (QDs) embedded in a planar microcavity on GaAs substrate. Low-density large QDs in the upper layer active for ~1.3 μm emission are fabricated by precisely controlling the indium deposition amount and applying a gradient indium flux in both QD layers. Time-resolved photoluminescence (PL) intensity suggested that the radiative lifetime of their exciton emission is 1.5~1.6 ns. The second-order correlation function of g (2)(0) < 0.5 which demonstrates a pure single-photon emission.

  5. Imaging of spectral-domain optical coherence tomography using a superluminescent diode based on InAs quantum dots emitting broadband spectrum with Gaussian-like shape

    Science.gov (United States)

    Shibata, Hiroshi; Ozaki, Nobuhiko; Yasuda, Takuma; Ohkouchi, Shunsuke; Ikeda, Naoki; Ohsato, Hirotaka; Watanabe, Eiichiro; Sugimoto, Yoshimasa; Furuki, Kenji; Miyaji, Kunio; Hogg, Richard A.

    2015-04-01

    We developed a low-coherence light source based on self-assembled InAs quantum dots (QDs) with controlled emission wavelengths and applied it to optical coherence tomography (OCT) imaging. A current-driven superluminescent diode (SLD) light source including four layers of QDs exhibits a broadband (80-nm-bandwidth) emission centered at approximately 1.2 µm with a Gaussian-like spectral shape at room temperature. Spectral-domain OCT (SD-OCT) using the QD-SLD as a light source was developed and imaging with the SD-OCT was demonstrated. The axial resolution was estimated to be approximately 8 µm in air and no apparent side lobes appeared beside the point spread function, indicating the effectiveness of the QD-SLD for high-resolution, noise-reduced OCT imaging.

  6. Structural and optical properties of silicon layers with InSb and InAs nanocrystals formed by ion-beam synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Komarov, F.; Vlasukova, L.; Greben, M.; Milchanin, O. [Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus); Zuk, J., E-mail: jotzet@hektor.umcs.lublin.pl [Maria Curie-Skłodowska University, Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin (Poland); Wesch, W.; Wendler, E. [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Togambaeva, A. [Al-Farabi Kazakh National University, 71 Al-Farabi Ave., 050040 Almaty (Kazakhstan)

    2013-07-15

    We have studied the formation of InSb and InAs precipitates with sizes of several nanometers in Si and SiO{sub 2}/Si by means of implantation of (Sb + In) or (As + In) ions with energies from 170 to 350 keV and fluencies from 2.8 to 3.5 × 10{sup 16} cm{sup −2} at 500 °C and subsequent annealing at 1050–1100 °C for 3–30 min. RBS, TEM/TED, RS and PL techniques were employed to characterize the implanted layers. A broad band in the region of 1.2–1.6 μm has been registered in the low-temperature PL spectra of both (Sb + In) and (As + In) implanted and annealed silicon crystals. It was shown that structural and optical properties of oxidized silicon crystals strongly depend on type of implanted species in silicon crystals.

  7. Current developments in laser ablation-inductively coupled plasma-mass spectrometry for use in geology, forensics, and nuclear nonproliferation research

    Energy Technology Data Exchange (ETDEWEB)

    Messerly, Joshua D. [Iowa State Univ., Ames, IA (United States)

    2008-08-26

    This dissertation focused on new applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The diverse fields that were investigated show the versatility of the technique. In Chapter 2, LA-ICP-MS was used to investigate the rare earth element (REE) profiles of garnets from the Broken Hill Deposit in New South Wales, Australia. The normalized REE profiles helped to shed new light on the formation of deposits of sulfide ores. This information may be helpful in identifying the location of sulfide ore deposits in other locations. New sources of metals such as Pg, Zn, and Ag, produced from these ores, are needed to sustain our current technological society. The application of LA-ICP-MS presented in Chapter 3 is the forensics analysis of automotive putty and caulking. The elemental analysis of these materials was combined with the use of Principal Components Analysis (PCA). The PCA comparison was able to differentiate the automotive putty samples by manufacturer and lot number. The analysis of caulk was able to show a differentiation based on manufacturer, but no clear differentiation was shown by lot number. This differentiation may allow matching of evidence in the future. This will require many more analyses and the construction of a database made up of many different samples. The 4th chapter was a study of the capabilities of LA-ICP-MS for fast and precise analysis of particle ensembles for nuclear nonproliferation applications. Laser ablation has the ability to spatially resolve particle ensembles which may contain uranium or other actinides from other particles present in a sample. This is of importance in samples obtained from air on filter media. The particle ensembles of interest may be mixed in amongst dust and other particulates. A problem arises when ablating these particle ensembles directly from the filter media. Dust particles other than ones of interest may be accidentally entrained in the aerosol of the ablated particle

  8. Literaturgeschichte anders gelesen. Ina Schaberts Englische Literaturgeschichte des 20. Jahrhunderts als Kosmos männlicher und weiblicher Stimmen Literary History Read Differently: Ina Schabert’s English Literary History of the Twentieth Century as a Cosmos of Male and Female Voices

    Directory of Open Access Journals (Sweden)

    Ingrid Hotz-Davies

    2007-03-01

    Full Text Available Ina Schaberts Abhandlung zur Britischen Literatur des zwanzigsten Jahrhunderts ist eine Literaturgeschichte der etwas anderen Art: die Literatur wird gesehen als ein Kosmos, der von männlichen und weiblichen Autoren bevölkert ist, die sich in einer ständigen Unterhaltung miteinander befinden, die mal freundlich, mal feindselig ausfallen mag, die aber als Unterhaltung die Literatur einer Epoche bestimmt. Schabert zeichnet eine detaillierte und faszinierende Abfolge dieser Interaktionen, die vom klassischen Modernismus über verschiedene politische ‚Realismen‘ zur postmodernen Welt der Diversifizierung der Ethnien und Geschlechteroptionen führt.Ina Schabert’s book on British literature of the twentieth century is a literary history with a difference: the literary cosmos is seen as peopled by male and female authors who are engaged in a continuous conversation with each other—sometimes hostile, sometimes friendly. The book offers a detailed and fascinating account of these interactions from Early Modernism through the years of various political ‘realisms’ to the Postmodern world of ethnic and gender diversity.

  9. ACT Verbal Prep Course

    CERN Document Server

    Standridge, Nathan

    2012-01-01

    Comprehensive Prep for ACT Verbal. Every year, students pay 1,000 and more to test prep companies to prepare for the verbal sections of the ACT. Now you can get the same preparation in a book. The verbal sections are not easy. There is no quick fix that will allow you to "beat" the ACT, but it is very learnable. If you study hard and master the techniques in this book, your score will improve-significantly. The ACT cannot be "beaten." But it can be mastered-through hard work, analytical thought, and by training yourself to think like a test writer. Many of the exercises in this book are design

  10. Quantum measurement act as a "speech act"

    CERN Document Server

    Schneider, J

    2005-01-01

    I show that the quantum measurement problem can be understood if the measurement is seen as a ``speech act'' in the sense of modern language theory. The reduction of the state vector is in this perspective an intersubjectice -- or better a-subjective -- symbolic process. I then give some perspectives on applications to the ``Mind-Body problem''.

  11. The Apocryphal Acts Of Andrew

    NARCIS (Netherlands)

    Bremmer, Jan N.

    2000-01-01

    Following the first three volumes of the new series on the Acts of John (1995), the Acts of Paul and Thecla (1996) and the Acts of Peter (1998), this new volume is devoted to the Acts of Andrew. After a study of the relationship between the Acts of Andrew and the Acts of Andrew and Matthias, the maj

  12. Marine Mammal Protection Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Mammal Protection Act (MMPA or Act) prohibits, with certain exceptions, the "take" of marine mammals in U.S. waters and by U.S. citizens on the high seas,...

  13. InAs quantum dot growth on Al{sub x}Ga{sub 1−x}As by metalorganic vapor phase epitaxy for intermediate band solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jakomin, R., E-mail: robertojakomin@xerem.ufrj.br [Campus de Xerém, Universidade Federal do Rio de Janeiro, UFRJ, Duque de Caxias-RJ (Brazil); Campus de Xerém, Universidade Federal do Rio de Janeiro, UFRJ, Duque de Caxias-RJ (Brazil); Kawabata, R. M. S.; Souza, P. L. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutoires–DISSE–PUC-Rio, RJ (Brazil); Pontificia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, Rio de Janeiro, 22452-900 RJ (Brazil); Mourão, R. T.; Pires, M. P. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutoires–DISSE–PUC-Rio, RJ (Brazil); Instituto de Física, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro-RJ (Brazil); Micha, D. N. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutoires–DISSE–PUC-Rio, RJ (Brazil); Instituto de Física, Universidade Federal do Rio de Janeiro, UFRJ, Rio de Janeiro-RJ (Brazil); Coordenação de Licenciatura em Física, CEFET/RJ, Petrópolis-RJ (Brazil); Xie, H.; Fischer, A. M.; Ponce, F. A. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

    2014-09-07

    InAs quantum dot multilayers have been grown using Al{sub x}Ga{sub 1−x}As spacers with dimensions and compositions near the theoretical values for optimized efficiencies in intermediate band photovoltaic cells. Using an aluminium composition of x = 0.3 and InAs dot vertical dimensions of 5 nm, transitions to an intermediate band with energy close to the ideal theoretical value have been obtained. Optimum size uniformity and density have been achieved by capping the quantum dots with GaAs following the indium-flush method. This approach has also resulted in minimization of crystalline defects in the epilayer structure.

  14. Measurements of the spin-orbit interaction and Landé g factor in a pure-phase InAs nanowire double quantum dot in the Pauli spin-blockade regime

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiyin; Huang, Shaoyun, E-mail: hqxu@pku.edu.cn, E-mail: syhuang@pku.edu.cn; Lei, Zijin [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Pan, Dong; Zhao, Jianhua [State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Xu, H. Q., E-mail: hqxu@pku.edu.cn, E-mail: syhuang@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Division of Solid State Physics, Lund University, Box 118, S-22100 Lund (Sweden)

    2016-08-01

    We demonstrate direct measurements of the spin-orbit interaction and Landé g factors in a semiconductor nanowire double quantum dot. The device is made from a single-crystal pure-phase InAs nanowire on top of an array of finger gates on a Si/SiO{sub 2} substrate and the measurements are performed in the Pauli spin-blockade regime. It is found that the double quantum dot exhibits a large singlet-triplet energy splitting of Δ{sub ST} ∼ 2.3 meV, a strong spin-orbit interaction of Δ{sub SO} ∼ 140 μeV, and a large and strongly level-dependent Landé g factor of ∼12.5. These results imply that single-crystal pure-phase InAs nanowires are desired semiconductor nanostructures for applications in quantum information technologies.

  15. Identificação do vírus causador de encefalomielite eqüina, Paraná, Brasil Identification of the encephalitis equine virus, Brazil

    Directory of Open Access Journals (Sweden)

    Zoraida Fernández

    2000-06-01

    Full Text Available OBJETIVO: No período de 1996 a 1999, um agente viral causador de encefalomielite afetou as populações de eqüinos em diferentes regiões do Estado do Paraná, Brasil. Objetivou-se realizar pesquisa sorológica na tentativa de isolar o vírus causador da doença. MÉTODOS: Em quatro municípios do Estado do Paraná, Brasil, foram coletados culicídeos com armadilha Shannon e isca humana, identificados e processados para isolamento de vírus. Em dois municípios estudados foram colhidas amostras de sangue de eqüinos para isolamento de vírus e para pesquisa sorológica. Os soros foram analisados pelo teste de inibição da hemaglutinação frente a diferentes antígenos de Alphavirus e Flavivirus. Aqueles que revelaram reações positivas-cruzadas foram analisados pelo teste de neutralização. RESULTADOS: Foram coletados culicídeos dos gêneros: Culex, Aedes, Mansonia, Coquillettidia, Psorophora, Sabethes, Wyeomyia e Limatus. Embora não sendo isolado o agente viral, foram detectados anticorpos hemaglutinantes para os vírus Encefalomielite eqüina do Leste, Mucambo, Pixuna, Maguari e St. Luis. Em doze amostras de soros foram detectados anticorpos neutralizantes para os vírus Encefalomielite eqüina do Leste. CONCLUSÕES: Foram coletadas espécies de culicídeos, considerados na bibliografia como vetores de vírus causadores de encefaliomielite buniavírus e outras arboviroses de importância epidemiológica. Pela presença de sintomas de encefalomielite e de anticorpos para o vírus Encefalomielite eqüina do Leste nos soros dos cavalos, supõe-se ser esse o vírus causador da doença nos eqüinos das regiões estudadas.INTRODUCTION: In the period of 1996-1999 some virus associated with encephalitis have been reported in horses from different regions of Paraná State, Brazil. To identify the etiologic agent associated with this illness, mosquitoes and serum samples were collected in the endemic area. METHODS: The study area corresponded to

  16. Use of Remotely Piloted Aircraft System (RPAS) in the analysis of historical landslide occurred in 1885 in the Rječina River Valley, Croatia

    Science.gov (United States)

    Dugonjić Jovančević, Sanja; Peranić, Josip; Ružić, Igor; Arbanas, Željko; Kalajžić, Duje; Benac, Čedomir

    2016-04-01

    Numerous instability phenomena have been recorded in the Rječina River Valley, near the City of Rijeka, in the past 250 years. Large landslides triggered by rainfall and floods, were registered on both sides of the Valley. Landslide inventory in the Valley was established based on recorded historical events and LiDAR imagery. The Rječina River is a typical karstic river 18.7km long, originating from the Gorski Kotar Mountains. The central part of the Valley, belongs to the dominant morphostructural unit that strikes in the northwest-southeast direction along the Rječina River. Karstified limestone rock mass is visible on the top of the slopes, while the flysch rock mass is present on the lower slopes and at the bottom of the Valley. Different types of movements can be distinguished in the area, such as the sliding of slope deposits over the flysch bedrock, rockfalls from limestone cliffs, sliding of huge rocky blocks, and active landslide on the north-eastern slope. The paper presents investigation of the dormant landslide located on the south-western slope of the Valley, which was recorded in 1870 in numerous historical descriptions. Due to intense and long-term rainfall, the landslide was reactivated in 1885, destroying and damaging houses in the eastern part of the Grohovo Village. To predict possible reactivation of the dormant landslide on the south-western side of the Valley, 2D stability back analyses were performed on the basis of landslide features, in order to approximate the position of sliding surface and landslide dimensions. The landslide topography is very steep, and the slope is covered by unstable debris material, so therefore hard to perform any terrestrial geodetic survey. Consumer-grade DJI Phantom 2 Remotely Piloted Aircraft System (RPAS) was used to provide the data about the present slope topography. The landslide 3D point cloud was derived from approximately 200 photographs taken with RPAS, using structure-from-motion (SfM) photogrammetry

  17. MBE Growth and STM Analysis of Surface Morphology and Reconstructions of InAs Films%InAs薄膜的分子束外延生长与表面形貌及表面重构分析

    Institute of Scientific and Technical Information of China (English)

    王继红; 罗子江; 周勋; 张毕禅; 郭祥; 丁召

    2013-01-01

    InAs films were prepared on InAs (001) substrate by utilizing the molecular beam epitaxy (MBE) technology. During the growth process of InAs films, reflection high energy electron diffraction (RHEED) intensity oscillations and patterns were used to measure and monitor the real-time growth rate and status. After growth and subsequent annealing, the sample was quenched down to room temperature then transferred into scanning tunneling microscope(STM) for observation. STM images confirmed that the surface morphology of this sample was atomically flat. Combined the RHEED patterns with STM images, it is speculated that the surface reconstruction of InAs films was mixture of/32(2×4) and α2(2 ×4).%利用带有反射高能电子衍射(RHEED)仪的分子束外延(MBE)方法,通过RHEED图像演变实时监控薄膜生长状况,采用RHEED强度振荡测量薄膜生长速率,在InAs(001)基片上同质外延InAs薄膜.利用扫描隧道显微镜(STM)对MBE生长的InAs薄膜表面形貌以及表面重构进行扫描分析,证实样品表面为原子级平整,并指出样品表面处于β2(2×4)与α2(2×4)两种重构混合的重构相.

  18. Synthesis and Crystal Structure of a Two-dimensional Silver(I)-Iron(III) Heteronuclear Coordination Polymer:{[Ag4Fe2(SCN)12(H2O)2] [(inaH)2(H2O)2]}n

    Institute of Scientific and Technical Information of China (English)

    LI,Xiu-Ling(李秀玲); TONG,Ming-Liang(童明良); NIU,De-Zhong(牛德仲); CHEN,Jiu-Tong(陈久桐)

    2004-01-01

    The 2-D heteronuclear coordination polymer {[Ag4Fe2(SCN)12(H2O)2] [(inaH)2(H2O)2]}n (1) (inaH is the abbreviation of protonated isonicotinic acid) with chemical formula C24H20Ag4Fe2N14O8S12 has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. The Ag2S2 rings connect two kinds of octahedral geometries of Fe(III) ions, [Fe(NCS)6]3- and [Fe(H2O)2(NCS)4]- units with bridging thiocyanate ions leading to 2-D [Ag4Fe2(SCN)12(H2O)2]2- anion framework. Four kinds of rings including the unprecedented thirty-two membered Ag4Fe4(SCN)8 rings share corners or edges in the 2-D anion layer structure. All thiocyanates coordinate to the metal ions according to the HSAB principle with N atoms binding to the Fe(III) ions and with S atoms binding to Ag(I) ions. Pronoated ina cations stabilize the layer structure as counter ions and hydrogen bonds were formed within the pronoated ina cations dimer and between the dimers and the lattice waters. Crystal data: Mr=1560.44, triclinic, P(1-) a=0.76082(1) nm, b=0.9234 nm, c=1.85611(4) nm, α=103.0170(10)°, β=93.7780(10)°, γ=97.4080(10), V=1.25385(3) nm3, Z=1, μ(Mo Kα)=2.650 mm-1, Dc=2.067 g·cm-3, F(000)=758, R1=0.0412, wR2=0.1003.

  19. 75 FR 63703 - Privacy Act of 1974; Privacy Act Regulation

    Science.gov (United States)

    2010-10-18

    ... CFR Part 261a Privacy Act of 1974; Privacy Act Regulation AGENCY: Board of Governors of the Federal...) is issuing a final rule to amend its regulation implementing the Privacy Act of 1974 (Privacy Act..., and applicants for Board employment, for access to their records under the Privacy Act; the amendment...

  20. The A.D. 1835 eruption of Volcán Cosigüina, Nicaragua: A guide for assessing local volcanic hazards

    Science.gov (United States)

    Scott, William E.; Gardner, Cynthia A.; Devoli, Graziella; Alvarez, Antonio

    2006-01-01

    The January 1835 eruption of Volcán Cosigüina in northwestern Nicaragua was one of the largest and most explosive in Central America since Spanish colonization. We report on the results of reconnaissance stratigraphic studies and laboratory work aimed at better defining the distribution and character of deposits emplaced by the eruption as a means of developing a preliminary hazards assessment for future eruptions. On the lower flanks of the volcano, a basal tephra-fall deposit comprises either ash and fine lithic lapilli or, locally, dacitic pumice. An overlying tephra-fall deposit forms an extensive blanket of brown to gray andesitic scoria that is 35–60 cm thick at 5–10 km from the summit-caldera rim, except southwest of the volcano, where it is considerably thinner. The scoria fall produced the most voluminous deposit of the eruption and underlies pyroclastic-surge and -flow deposits that chiefly comprise gray andesitic scoria. In northern and southeastern sectors of the volcano, these flowage deposits form broad fans and valley fills that locally reach the Gulf of Fonseca. An arcuate ridge 2 km west of the caldera rim and a low ridge east of the caldera deflected pyroclastic flows northward and southeastward. Pyroclastic flows did not reach the lower west and southwest flanks, which instead received thick, fine-grained, accretionary-lapilli–rich ashfall deposits that probably derived chiefly from ash clouds elutriated from pyroclastic flows. We estimate the total bulk volume of erupted deposits to be ∼6 km3. Following the eruption, lahars inundated large portions of the lower flanks, and erosion of deposits and creation of new channels triggered rapid alluviation. Pre-1835 eruptions are poorly dated; however, scoria-fall, pyroclastic-flow, and lahar deposits record a penultimate eruption of smaller magnitude than that of 1835. It occurred a few centuries earlier—perhaps in the fifteenth century. An undated sequence of thick tephra-fall deposits on

  1. Theoretical analyses of the elastic and electronic properties of InAs QDs and QD-in-WELL structures grown on GaAs high index substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bennour, M., E-mail: mnbnnr@gmail.com [Micro-Optoelectronic and Nanostructures Laboratory, Department of Physics, Faculty of Sciences, Monastir University, Environment Street, 5019 Monastir (Tunisia); Bouzaiene, L.; Saidi, F. [Micro-Optoelectronic and Nanostructures Laboratory, Department of Physics, Faculty of Sciences, Monastir University, Environment Street, 5019 Monastir (Tunisia); Sfaxi, L. [Micro-Optoelectronic and Nanostructures Laboratory, Sousse University (Tunisia); Maaref, H. [Micro-Optoelectronic and Nanostructures Laboratory, Department of Physics, Faculty of Sciences, Monastir University, Environment Street, 5019 Monastir (Tunisia)

    2015-10-25

    We report a theoretical study of the wetting layer thickness, In{sub x}Ga{sub (1−x)}As quantum-well thickness and Indium composition effects on the physical properties of InAs quantum dots (QDs) and quantum dots-in-well (QD-in-WELL) grown on GaAs high index substrates. Finite element method is used to calculate the strain, piezoelectric field distributions and the electronic structure. Coulomb interaction has been taken as a perturbation in the interband transition energy. The ground–state transition energy is influenced by the wetting layer thickness (WL) and the substrate orientation; however, it is not affected by the InGaAs quantum-well thickness. We have found that the tensile strain at the interface is the main factor responsible for the difficulty of self-assembled InAs QDs formation on GaAs(111) substrate. On the other hand, the stability of the relaxed strain into QD–IN–WELL depended on the Indium composition and the quantum-well thickness as well as the orientation substrate. The appropriate Indium composition in the InGaAs quantum-well is found to be 0.3 for the QD–IN–WELL grown on GaAs(111) and 0.2 for the QD–IN–WELL grown on GaAs(119). This work can be helpful to controlling the wavelength of QD–IN–WELL grown on high index substrates by changing the In composition or the quantum well-thickness. - Graphical abstract: The piezoelectric field was found to be more important in large QD than that of small QD which contribute to a little blue shift between small and large QD, when the substrate disorientation increased from (119) to (111). - Highlights: • Finite element method used to calculate strain, piezoelectric field and energy gap. • Physical properties of InAs/GaAs(11n) QDs and InGaAs/InAs/InGaAs/GaAs(11n) QD-in Well. • Stability of relaxed strain into quantum dots and quantum dots-in-well was discussed. • Tensile strain interface is responsible of difficulty self-assembled InAs/GaAs(111)QD.

  2. National Environmental Policy Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Environmental Policy Act (NEPA) was the first major environmental law in the United States and established national environmental policies for the...

  3. Acts of Research

    DEFF Research Database (Denmark)

    Nelund, Sidsel

    with an awareness of larger political, economic, geographical and art-related aspects. The concept of ‘acts of research’ is suggested as a way to understand knowledge production as a creative act in which research carried out in relation to a specific material challenges and resists the protocols of conventional...... described as knowledge producers and exhibitions and art works as instances of knowledge production. Acts of Research: Knowledge Production in Contemporary Arts between Knowledge Economy and Critical Practices analyses this development. The academic discussion of knowledge production in the arts has taken...... place mostly in seminars and articles, in which knowledge is often discussed as an intrinsic quality of the artwork. Acts of Research, however, is devoted to studying the rise of knowledge production in contemporary art from the perspective of artistic, curatorial and educational research...

  4. Abandoned Shipwreck Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Abandoned Shipwreck Act of 1987 (ASA) affirms the authority of state governments to claim ownership to, protect, and manage abandoned shipwrecks on state...

  5. Marine Pollution Prevention Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Pollution Prevention Act of 2008 implements the International Convention for the Prevention of Pollution from Ships, including related Protocols (MARPOL)...

  6. Clean Water Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Clean Water Act (CWA) establishes the basic structure for regulating discharges of pollutants into U.S. waters and regulating quality standards for surface...

  7. Affordable Care Act (ACA)

    Data.gov (United States)

    Social Security Administration — The Affordable Care Act (ACA) is a federal statute enacted with a goal of increasing the quality and affordability of health insurance. Through a web service, CMS...

  8. Endangered Species Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of the Endangered Species Act (ESA) is to protect and recover imperiled species and the ecosystems upon which they depend. The U.S. Fish and Wildlife...

  9. ACT250 Districts

    Data.gov (United States)

    Vermont Center for Geographic Information — The ACT 250 Districts layer is part of a larger dataset that contains administrative boundaries for Vermont's Agency of Natural Resources. The dataset includes...

  10. Energy Policy Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Energy Policy Act (EPA) addresses energy production in the United States, including: (1) energy efficiency; (2) renewable energy; (3) oil and gas; (4) coal; (5)...

  11. The Corporations Act 2001

    OpenAIRE

    Bostock, Tom

    2002-01-01

    The author outlines reforms made in Australia in the area of company law with an analysis of the Corporations Act 2001, which along with the Australian Securities and Investments Commission Act 2001 comprises Corporations legislation in Australia. Article by Tom Bostock (a partner in the law firm Mallesons Stephen Jaques, Melbourne, Australia). Published in Amicus Curiae - Journal of the Institute of Advanced Legal Studies and its Society for Advanced Legal Studies. The Journal is produced by...

  12. Comentario jurisprudencial sobre la sentencia del Tribunal Constitucional Rol No 2273-12-INA sobre inaplicabilidad de normas del D.L. No 10.094 que establece normas sobre los extranjeros en Chile y las matizaciones de la Rol No 2257-12-INA

    Directory of Open Access Journals (Sweden)

    Liliana Galdámez Zelada

    2013-01-01

    Full Text Available Este trabajo analiza la sentencia de inaplicabilidad por inconstitucionalidad dictada por el Tribunal Constitucional en relación al inciso primero del art. 13 del D.L. No 1.094, que regula la situación de los extranjeros en Chile. La norma fue dictada por la Junta Militar el año 1975. Revisaremos tres ámbitos de la sentencia, la invocación del DIDH y Derecho Constitucional como límite frente a los poderes del Estado; la formulación de un estatuto jurídico para los extranjeros que el Tribunal Constitucional enuncia y la declaración de inaplicabilidad por inconstitucionalidad de una norma preconstitucional y preconvencional por vulnerar derechos fundamentales. En la parte final revisaremos los criterios posteriores contenidos en la Rol No 2257-12-INA.

  13. Direct observation of strain in InAs quantum dots and cap layer during molecular beam epitaxial growth using in situ X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, Kenichi; Ohshita, Yoshio; Kamiya, Itaru, E-mail: kamiya@toyota-ti.ac.jp [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan); Suzuki, Hidetoshi [Faculty of Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai-nishi, Miyazaki 889-2192 (Japan); Sasaki, Takuo; Takahasi, Masamitu [Quantum Beam Science Center, Japan Atomic Energy Agency, Koto 1-1-1, Sayo-cho, Hyogo 679-5148 (Japan)

    2015-11-14

    Direct measurements on the growth of InAs quantum dots (QDs) and various cap layers during molecular beam epitaxy are performed by in situ X-ray diffraction (XRD). The evolution of strain induced both in the QDs and cap layers during capping is discussed based on the XRD intensity transients obtained at various lattice constants. Transients with different features are observed from those obtained during InGaAs and GaAs capping. The difference observed is attributed to In-Ga intermixing between the QDs and the cap layer under limited supply of In. Photoluminescence (PL) wavelength can be tuned by controlling the intermixing, which affects both the strain induced in the QDs and the barrier heights. The PL wavelength also varies with the cap layer thickness. A large redshift occurs by reducing the cap thickness. The in situ XRD observation reveals that this is a result of reduced strain. We demonstrate how such information about strain can be applied for designing and preparing novel device structures.

  14. GaAsSb/GaAsN short-period superlattices as a capping layer for improved InAs quantum dot-based optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Utrilla, A. D.; Ulloa, J. M., E-mail: jmulloa@isom.upm.es; Guzman, A.; Hierro, A. [Institute for Systems based on Optoelectronics and Microtechnology (ISOM) and Departamento de Ingeniería Electrónica, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Reyes, D. F.; González, D.; Ben, T. [Departamento de Ciencia de los Materiales e IM y QI, Universidad de Cádiz, 11510 Puerto Real (Cádiz) (Spain)

    2014-07-28

    The application of a GaAsSb/GaAsN short-period superlattice capping layer (CL) on InAs/GaAs quantum dots (QDs) is shown to be an option for providing improved luminescence properties to this system. Separating both GaAsSb and GaAsN ternaries during the growth in 2 monolayer-thick phases solves the GaAsSbN immiscibility-related problems. Strong fluctuations in the CL composition and strain field as well as in the QD size distribution are significantly reduced, and a more regular CL interface is also obtained. Room-temperature (RT) photoluminescence (PL) is obtained for overall N contents as high as 3%, yielding PL peak wavelengths beyond 1.4 μm in samples with a type-II band alignment. High external quantum efficiency electroluminescence and photocurrent from the QD ground state are also demonstrated at RT in a single QD-layer p-i-n device. Thus, it becomes possible to combine and transfer the complementary benefits of Sb- and N-containing GaAs alloys to InAs QD-based optoelectronics.

  15. Optically pumped 1.3  μm room-temperature InAs quantum-dot micro-disk lasers directly grown on (001) silicon.

    Science.gov (United States)

    Wan, Yating; Li, Qiang; Liu, Alan Y; Gossard, Arthur C; Bowers, John E; Hu, Evelyn L; Lau, Kei May

    2016-04-01

    Direct integration of high-performance laser diodes on silicon will dramatically transform the world of photonics, expediting the progress toward low-cost and compact photonic integrated circuits (PICs) on the mainstream silicon platform. Here, we report, to the best of our knowledge, the first 1.3 μm room-temperature continuous-wave InAs quantum-dot micro-disk lasers epitaxially grown on industrial-compatible Si (001) substrates without offcut. The lasing threshold is as low as hundreds of microwatts, similar to the thresholds of identical lasers grown on a GaAs substrate. The heteroepitaxial structure employed here does not require the use of an absorptive germanium buffer and/or dislocation filter layers, both of which impede the efficient coupling of light from the laser active regions to silicon waveguides. This allows for full compatibility with the extensive silicon-on-insulator (SOI) technology. The large-area virtual GaAs (on Si) substrates can be directly adopted in various mature in-plane laser configurations, both optically and electrically. Thus, this demonstration represents a major advancement toward the commercial success of fully integrated silicon photonics.

  16. INCIDÊNCIA DE ANEMIA INFECCIOSA EQÜINA NO ESTADO DE GOIÁS INFECTIOUS ANEMIA INCIDENCE IN EQUINES IN THE GOIÁS STATE, BRAZIL

    Directory of Open Access Journals (Sweden)

    Jales Henrique Freitas Curado

    2007-09-01

    Full Text Available

    Dos 2.123 soros de eqüinos, examinados pelo método de COGGINS, encontrou-se a taxa de 3,7% de reagentes positivos para a anemia infecciosa eqüina. Estes dados indicam que, nos municípios estudados no Estado de Goiás, os índices de prevalência estão dentro dos limites esperados, especialmente nos municípios localizados em áreas alagadiças, onde a veiculação da doença é mais intensa.

    From 2,123 equine serum examined by COGGINS method it was found 3.7% positive reagents for equine infections anemia. The data indicate that, for the counties studied in the State of Goiás, prevalence rates are within the expected range, especially in the counties with flooded areas where disease incidence is more intense.

  17. Comparison between theoretical and experimental results for energy states of two-dimensional electron gas in pseudomorphically strained InAs high-electron-mobility transistors

    Science.gov (United States)

    Nishio, Yui; Tange, Takahiro; Hirayama, Naomi; Iida, Tsutomu; Takanashi, Yoshifumi

    2014-01-01

    The energy states of a two-dimensional electron gas (2DEG) in high-electron-mobility transistors with a pseudomorphically strained InAs channel (PHEMTs) were analyzed rigorously using a recently established theory that takes into account the nonparabolicity of the conduction band of the channel layer. The sheet density of the 2DEG in InxGa1-xAs-PHEMTs and the drain I-V characteristics of those devices were calculated theoretically and compared with the density and characteristics obtained experimentally. Not only the calculated threshold voltage (VTH) but also the calculated transconductance agreed fairly well with the corresponding values obtained experimentally. When the effects of the compositions of the InxGa1-xAs subchannel layer in the composite channel and the channel layer on energy states of 2DEG were investigated in order to establish a guiding principle for a design of the channel structure in PHEMTs, it was found that VTH is determined by the effective conduction-band offset energy ΔEC between the InAlAs barrier and the channel layers.

  18. Two-photon interference and coherent control of single InAs quantum dot emissions in an Ag-embedded structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X., E-mail: iu.xiangming@nims.go.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021 (Japan); National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Kumano, H.; Nakajima, H.; Odashima, S.; Asano, T.; Suemune, I. [Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021 (Japan); Kuroda, T. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2014-07-28

    We have recently reported the successful fabrication of bright single-photon sources based on Ag-embedded nanocone structures that incorporate InAs quantum dots. The source had a photon collection efficiency as high as 24.6%. Here, we show the results of various types of photonic characterizations of the Ag-embedded nanocone structures that confirm their versatility as regards a broad range of quantum optical applications. We measure the first-order autocorrelation function to evaluate the coherence time of emitted photons, and the second-order correlation function, which reveals the strong suppression of multiple photon generation. The high indistinguishability of emitted photons is shown by the Hong-Ou-Mandel-type two-photon interference. With quasi-resonant excitation, coherent population flopping is demonstrated through Rabi oscillations. Extremely high single-photon purity with a g{sup (2)}(0) value of 0.008 is achieved with π-pulse quasi-resonant excitation.

  19. High efficiency low threshold current 1.3 μm InAs quantum dot lasers on on-axis (001) GaP/Si

    Science.gov (United States)

    Jung, Daehwan; Norman, Justin; Kennedy, M. J.; Shang, Chen; Shin, Bongki; Wan, Yating; Gossard, Arthur C.; Bowers, John E.

    2017-09-01

    We demonstrate highly efficient, low threshold InAs quantum dot lasers epitaxially grown on on-axis (001) GaP/Si substrates using molecular beam epitaxy. Electron channeling contrast imaging measurements show a threading dislocation density of 7.3 × 106 cm-2 from an optimized GaAs template grown on GaP/Si. The high-quality GaAs templates enable as-cleaved quantum dot lasers to achieve a room-temperature continuous-wave (CW) threshold current of 9.5 mA, a threshold current density as low as 132 A/cm2, a single-side output power of 175 mW, and a wall-plug-efficiency of 38.4% at room temperature. As-cleaved QD lasers show ground-state CW lasing up to 80 °C. The application of a 95% high-reflectivity coating on one laser facet results in a CW threshold current of 6.7 mA, which is a record-low value for any kind of Fabry-Perot laser grown on Si.

  20. Investigation of single-layer/multilayer self-assembled InAs quantum dots on GaAs1-xSbx/GaAs composite substrates

    Science.gov (United States)

    Tang, Dinghao; Kim, Yeongho; Faleev, Nikolai; Honsberg, Christiana B.; Smith, David J.

    2015-09-01

    The structure-performance properties of single-layered and multi-layered InAs/GaAs1-xSbx quantum dot (QD) system, grown by molecular beam epitaxy on GaAs (001) substrates, have been investigated as a function of Sb concentration. Electron microscopy observations showed no significant crystalline defects for the single-layered InAs QDs (Sb 20%). X-ray diffraction analysis revealed that the increase of Sb concentration from 7.3% to 10.2% for the multi-layered QDs increased the strain relaxation from 0% to ˜23% and the dislocation density of GaAsSb layers went up to 3.6 × 109 cm-2. The peak energy of QD luminescence was red-shifted with increasing Sb concentration due to reduced strain inside QDs. Moreover, the carrier lifetime of the QDs was highly improved from 1.7 to 36.7 ns due to weak hole confinement as the Sb concentration was increased from 7.3% to 10.2%. These structures should be highly promising as the basis for photovoltaic solar-cell applications. Finally, the increased Sb concentration increased the thermal activation energy of electrons confined in the QDs from 163.7 to 206.8 meV, which was indicative of the improved thermal stability with Sb concentration.