6,636 research outputs found

    Full counting statistics of Majorana interferometers

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    We study the full counting statistics of interferometers for chiral Majorana fermions with two incoming and two outgoing Dirac fermion channels. In the absence of interactions, the FCS can be obtained from the 4×44\times4 scattering matrix SS that relates the outgoing Dirac fermions to the incoming Dirac fermions. After presenting explicit expressions for the higher-order current correlations for a modified Hanbury Brown-Twiss interferometer, we note that the cumulant-generating function can be interpreted such that unit-charge transfer processes correspond to two independent half-charge transfer processes, or alternatively, to two independent electron-hole conversion processes. By a combination of analytical and numerical approaches, we verify that this factorization property holds for a general SO(4)SO(4) scattering matrix, i.e. for a general interferometer geometry.Comment: 22 pages, 3 figures, contributed to the special issue of Physica E "Frontiers in Quantum Electronic Transport - In Memory of Markus Buttiker

    Classification Results of Hadamard Matrices

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    In 1893 Hadamard proved that for any n x n matrix A over the complex numbers, with all of its entries of absolute value less than or equal to 1, it necessarily follows that |det(A)| ≤ nn/2 [n raised to the power n divided by two], with equality if and only if the rows of A are mutually orthogonal and the absolute value of each entry is equal to 1 (See [2], [3]). Such matrices are now appropriately identified as Hadamard matrices, which provides an active area of research in both theoretical and applied fields of the sciences. In pure mathematics, Hadamard matrices are of interest due to their intrisic beauty as well as their applications to areas such as combinatorics, information theory, optics, operator algebras and quantum mechanics. In this text we will introduce some fundamental properties of Hadamard matrices as well as provide a proofs of some classification results for real Hadamard matrices

    positions of place: converging viewpoints in visual communication

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    This thesis includes a body of work that explores our visual relationship to the physical spaces and places we inhabit in our everyday lives. Today we live in a complex world where we are bombarded with fragments of information and inundated with distractions. As designers, we are equipped with tools and methods that allow us to experience and interpret our environment through multi-faceted perspectives and from different viewpoints. My approach to graphic design adopts techniques and practices from a mix of different disciplines. The work focuses on a design process that alternates between the parallel depiction of first-person and third-person vantage points mediated through contemporary technologies

    Advanced Environmental Monitoring and Control Program: Strategic Plan

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    Human missions in space, from short-duration shuttle missions lasting no more than several days to the medium-to-long-duration missions planned for the International Space Station, face a number of hazards that must be understood and mitigated for the mission to be carried out safely. Among these hazards are those posed by the internal environment of the spacecraft itself; through outgassing of toxic vapors from plastics and other items, failures or off-nominal operations of spacecraft environmental control systems, accidental exposure to hazardous compounds used in experiments: all present potential hazards that while small, may accumulate and pose a danger to crew health. The first step toward mitigating the dangers of these hazards is understanding the internal environment of the spacecraft and the compounds contained within it. Future spacecraft will have integrated networks of redundant sensors which will not only inform the crew of hazards, but will pinpoint the problem location and, through analysis by intelligent systems, recommend and even implement a course of action to stop the problem. This strategic plan details strategies to determine NASA's requirements for environmental monitoring and control systems for future spacecraft, and goals and objectives for a program to answer these needs

    NASA Virtual Institutes: International Bridges for Space Exploration

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    NASA created the first virtual institute, the NASA Astrobiology Institute (NAI), in 2009 with an aim toward bringing together geographically disparate and multidisciplinary teams toward the goal of answering broad questions in the then-new discipline of astrobiology. With the success of the virtual institute model, NASA then created the NASA Lunar Science Institute (NLSI) in 2008 to address questions of science and human exploration of the Moon, and then the NASA Aeronautics Research Institute (NARI) in 2012 which addresses key questions in the development of aeronautics technologies. With the broadening of NASA's human exploration targets to include Near Earth Asteroids and the moons of Mars as well as the Moon, the NLSI morphed into the Solar System Exploration Research Virtual Institute (SSERVI) in 2012. SSERVI funds domestic research teams to address broad questions at the intersection of science and human exploration, with the underlying principle that science enables human exploration, and human exploration enables science. Nine domestic teams were funded in 2014 for a five-year period to address a variety of different topics, and nine international partners (with more to come) also work with the U.S. teams on a variety of topics of mutual interest. The result is a robust and productive research infrastructure that is not only scientifically productive but can respond to strategic topics of domestic and international interest, and which develops a new generation of researchers. This is all accomplished with the aid of virtual collaboration technologies which enable scientific research at a distance. The virtual institute model is widely applicable to a range of space science and exploration problems

    The NASA Solar System Exploration Virtual Institute: International Efforts in Advancing Lunar Science with Prospects for the Future

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    The NASA Solar System Exploration Research Virtual Institute (SSERVI), originally chartered in 2008 as the NASA Lunar Science Institute (NLSI), is chartered to advance both the scientific goals needed to enable human space exploration, as well as the science enabled by such exploration. NLSI and SSERVI have in succession been "institutes without walls," fostering collaboration between domestic teams (7 teams for NLSI, 9 for SSERVI) as well as between these teams and the institutes' international partners, resulting in a greater global endeavor. SSERVI teams and international partners participate in sharing ideas, information, and data arising from their respective research efforts, and contribute to the training of young scientists and bringing the scientific results and excitement of exploration to the public. The domestic teams also respond to NASA's strategic needs, providing community-based responses to NASA needs in partnership with NASA's Analysis Groups. Through the many partnerships enabled by NLSI and SSERVI, scientific results have well exceeded initial projections based on the original PI proposals, proving the validity of the virtual institute model. NLSI and SSERVI have endeavored to represent not just the selected and funded domestic teams, but rather the entire relevant scientific community; this has been done through many means such as the annual Lunar Science Forum (now re-named Exploration Science Forum), community-based grass roots Focus Groups on a wide range of topics, and groups chartered to further the careers of young scientists. Additionally, NLSI and SSERVI have co-founded international efforts such as the pan-European lunar science consortium, with an overall goal of raising the tide of lunar science (and now more broadly exploration science) across the world

    Functional Analysis and the Reappraisal of Faculty Papers: A Practical Application

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    In 2009, Provenance published an article examining the reappraisal and functional analysis of faculty papers in university archives. The present article examines a case study of the practical application of the model that emerged

    Functional Analysis and the Reappraisal of Faculty Papers

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    Many repositories at American colleges and universities hold the official records of their institutions as well as the personal papers of individuals. Archivists appraise these different materials—institutional records and personal papers—using separate theoretical perspectives. They tend to bring a records-management view of evidential value to the appraisal of institutional records and a curator’s eye for informational and intrinsic values to personal manuscripts. There is one collecting category common to university repositories, however, that requires a hybrid approach. Falling between the two broad categories of university records and personal manuscripts are the papers of university faculty members. Studies of the holdings of university archives indicate that faculty papers are well represented in the archival record

    The Global Exploration Roadmap: Opportunities for Lunar Science

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    The Global Exploration Roadmap (GER) has been developed by the International Space Exploration Coordination Group (ISECG comprised of 14 space agencies) to define various pathways to getting humans beyond low Earth orbit and eventually to Mars. Such pathways include visiting asteroids or the Moon before going on to Mars. This document has been written at a very high level and many details are still to be determined. However, a number of important papers regarding international space exploration can form a basis for this document.This poster will focus on developing the Lunar Vicinity scenario by adding detail via mapping a number of recent reportsdocuments into the GER. The documents highlighted here are in no way meant to be all encompassing and other documents can and should be added, (e.g., the JAXA Space Exploration Roadmap). This exercise is intended to demonstrate that existing documents can be mapped into the GER despite the major differences in granularity, and that this mapping is a way to promote broader national and international buy-in to the Lunar Vicinity scenario.The documents used here are: the Committee on Space Research (COSPAR) Panel on Exploration report on developing a global space exploration program, the Strategic Knowledge Gaps (SKGs) report from the Lunar Exploration Analysis Group (LEAG), the Lunar Exploration Roadmap developed by LEAG, the National Research Council report Scientific Context for the Exploration of the Moon (SCEM), and two journal articles, the scientific rationale for resuming lunar surface exploration, and the astrobiological benefits of human space exploration.In addition, the ISECG is in the process of developing a Science White Paper (SWP) to accompany the next edition of the GER, due in late 2016. The SWP will be an important tool to communicate science which will be able to be accomplished at human exploration destinations to policymakers. This abstract will discuss the process of developing this SWP and ways in which the global science community can become engaged in its development
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