549 research outputs found

    Statistics of Wave Functions in Disordered Systems with Applications to Coulomb Blockade Peak Spacing

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    Despite considerable work on the energy-level and wavefunction statistics of disordered quantum systems, numerical studies of those statistics relevant for electron-electron interactions in mesoscopic systems have been lacking. We plug this gap by using a tight-binding model to study a wide variety of statistics for the two-dimensional, disordered quantum system in the diffusive regime. Our results are in good agreement with random matrix theory (or its extensions) for simple statistics such as the probability distribution of energy levels or spatial correlation of a wavefunction. However, we see substantial disagreement in several statistics which involve both integrating over space and different energy levels, indicating that disordered systems are more complex than previously thought. These are exactly the quantities relevant to electron-electron interaction effects in quantum dots; in fact, we apply these results to the Coulomb blockade, where we find altered spacings between conductance peaks and wider spin distributions than traditionally expected.Comment: Accepted for publication in Phys Rev

    Biomechanical Evaluation of Recurrent Dissociation of Modular Humeral Prostheses

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    The purpose of the study was to evaluate the force and torque required to dissociate a humeral head from the unimplanted modular total shoulder replacement system from different manufacturers and to determine if load and torque to dissociation are reduced in the presence of bodily fluids. Impingement, taper contamination, lack of compressive forces, and interference of taper fixation by the proximal humerus have all been reported as possible causes for dissociation. Experimental values determined in this research were compared with literature estimates of dissociation force of the humeral head under various conditions to gain more understanding of the causes of recurrent dissociations of the humeral head. This study examined biomechanical properties under dry and wet conditions under clinically practiced methods. Mean load to dissociation (1513 N ± 508 N) was found to be greater than that exerted by the activities of daily living (578 N) for all implants studied. The mean torque to dissociation was (49.77 N·m ± 19.07 N·m). Analysis of R2 correlation coefficients and p-values (α = 0.05) did not show any significant correlation between dry/bovine, dry/wet, or wet/bovine for load, displacement, or torsional stiffness in the majority of tests performed. Wetting the taper with water or bovine serum did not reduce the dissociation force to a statistically significant degree. Torque and lack of compressive forces at the rotator cuff may be the cause of dissociation at values less than those of activities of daily living. Torque data are provided by this study, but further research is needed to fully appreciate the role of torque in recurrent dissociations

    ID, GPS Tracking, 24/7 Tag Link for CubeSats and Constellations: Flight Results

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    The tiny 40-gram EyeStar-Tag processor, GPS, and radio link will ID its satellite with GPS and critical status data within a minute after turn-on. The autonomous low power EyeStar Tag GPS (20mW for 3D lock) is now at TRL-9 based on the successful release and operation of the Spaceflight Inc. ring on the 1/24/2021 rideshare launch. The orbit (530 km polar) was projected using GPS seven element arrays to generate, on the fly, the future ephemeris predictions while monitoring critical fight systems. The Tag continues to transmit over the Globalstar network of satellites and ground stations the GPS elements and status with low latency of seconds, even if the primary satellite fails or stops. Whether dead or alive, orbital elements and TLEs for debris tracking, attitude, and ID are available to the 18th Squadron. AFWERX’s SBIR investment helped fast track the Black Box and Tag systems. Key enablers and new architecture are flight referenced for 30 ThinSat constellation launched in February 2021 NG-15. With the Globalstar constellation NSL can monitor a satellite 24/7 anywhere in LEO orbits with data available anytime, without the need for expensive ground stations. With a 100% success in orbit using the NSL EyeStar processor and Globalstar comm systems (110+ radios in space with several tumbling) can contribute to the commercial, educational, and research small satellite market that is rapidly growing. The EyeStar radio is ideal for the next step to advance many NASA, DOD, commercial, and STEM satellites now that appropriate FCC, NTIA, and ITU licenses have all been approved. The aircraft Black Box is well known and is essential for crash diagnostics after the fact, but in addition, the satellite Black Box and processor will operate in Telemetry Tracking and Command (TT&C) mode during the whole mission and will continue TT&C in orbit after a completed or failed mission. The Black Box transmits vital data, health and safety information, GPS, and summary data while in orbit for 24/7 coverage. With its included solar arrays, the Black Box would operate for many years after the primary satellite fails so that essential data and tracking is continuous, and altitude known. If the satellite reawakens after some long failure, the Black Box reports the new status, and the satellite may be reactivated. NSL customers have experienced this wake-up mode after a year on one of our Black Box/EyeStar communication processors after an unexpected two-month “dead” phase and wake. The “dead” satellite was reactivated

    Prospectus, December 11, 1975

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    LETTERS TO THE EDITOR; IOC: Greetings to campus; Final Exam Schedule; To the Students of Parkland College
; PC News in brief: Christmas Concerts, Chili Supper; Far Out Planet; Anti-football views expressed at meeting; Distaff Side; Skylines; P/C College Theatre plays well recieved; Acupuncture Expert needles P.C. students; Toys for Tots; Vinyl Love; Two compete at Bradley debate; For Santa Claus: Little Jimmy\u27s list; Country Bouquet: Chicano Country; Exotic Dishes tasted by language classes; Rape - $150; Good News; Diana Hill, Scholarship Recipient; The Kaleidoscope; Forum; Reading skills improvement program offered at Parkland; Ike\u27s reply; Mitchell Interview; Prospectus Photo Contest; Christmas Greetings; Classified; Fast Freddy\u27s football forecast; Cobra\u27s Corner; Cobras downed 82-81 in OT; Sports Views; Davidson returns against home team; Henrichs Cut to six in 2nd loss; Lanky Warriors edge Cobrashttps://spark.parkland.edu/prospectus_1975/1000/thumbnail.jp

    Resource-Bound Quantification for Graph Transformation

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    Graph transformation has been used to model concurrent systems in software engineering, as well as in biochemistry and life sciences. The application of a transformation rule can be characterised algebraically as construction of a double-pushout (DPO) diagram in the category of graphs. We show how intuitionistic linear logic can be extended with resource-bound quantification, allowing for an implicit handling of the DPO conditions, and how resource logic can be used to reason about graph transformation systems

    Human Factors Operability Timeline Analysis to Improve the Processing Flow of the Orion Spacecraft

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    The Constellation Program (CxP) Orion vehicle goes through several areas and stages of processing before its launched at the Kennedy Space Center. In order to have efficient and effective processing, all of the activities need to be analyzed. This was accomplished by first developing a timeline of events that included each activity, and then each activity was analyzed by operability experts and human factors experts with spacecraft processing experience. This papers focus is to explain the results and the process for developing this human factors operability timeline analysis to improve the processing flow of Orion

    Standardising outcomes for clinical trials and systematic reviews

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    Fifteen years ago, what was to become OMERACT met for the first time in The Netherlands to discuss ways in which the multitude of outcomes in assessments of the effects of treatments for rheumatoid arthritis might be standardised. In Trials, Tugwell et al have described the need for, and success of, this initiative [1] and Cooney and colleagues have set out their plans for a corresponding initiative for ulcerative colitis [2]. Why do we need such initiatives? What\u27s the problem? And are these and other initiatives the solution

    Scientific response to a cluster of shark bites

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    1. Shark bites are of high public concern globally. Information on shark occurrence and behaviour, and of the effects of human behaviours, can help understand the drivers of shark-human interactions. In Australia, a number of shark bite clusters occurred over the last decade. One of these took place in Cid Harbour the Whitsundays, Queensland, a region for which little was known about the shark community. Here, we describe and evaluate the research in response to that shark bite cluster. 2. Fishing methods, acoustic and satellite tracking, and baited remote underwater video cameras (BRUVs) were used to identify the shark species using Cid Harbour, estimate relative abundance, and describe habitat use and residency. Side-scan sonar and BRUVs were also used to assess prey availability. Recreational users were surveyed to understand human behaviour and their awareness and perceptions of ‘Shark Smart’ behaviours. This allowed shark occurrence and behaviour to be interpreted in the context of human behaviours in the Harbour. 3. Eleven shark species were identified. Relative abundance was not unusually high, and residency in Cid Harbour was typically low. For example, 79% of acoustically tagged sharks visited the harbour on <10% days at liberty. Shark prey was available year-round. Notably, anchored boats regularly conduct activities that can attract sharks (dumping food scraps, provisioning and cleaning fish). 4. Alone, the methods used in this study had variable success, but combined they provided a large amount of complementary information. Including a social science component in the research response to the shark bite incidents allowed for a more holistic understanding of the Cid Harbour bite incidents. 5. This study did not identify anything unusual about the shark community that could have contributed to the Cid Harbour shark bite cluster. However, the three incidents involved people bitten almost instantly after entering the water, which is unusual and suggests that feeding/attracting sharks to boats could have been a contributor and also that any species capable of biting humans could have been responsible. 6. The eradication of activities that attract sharks to areas where people enter the water may reduce shark bite risk
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