5,450 research outputs found

    Rescuing Complementarity With Little Drama

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    The AMPS paradox challenges black hole complementarity by apparently constructing a way for an observer to bring information from the outside of the black hole into its interior if there is no drama at its horizon, making manifest a violation of monogamy of entanglement. We propose a new resolution to the paradox: this violation cannot be explicitly checked by an infalling observer in the finite proper time they have to live after crossing the horizon. Our resolution depends on a weak relaxation of the no-drama condition (we call it "little drama") which is the "complementarity dual" of scrambling of information on the stretched horizon. When translated to the description of the black hole interior, this implies that the fine-grained quantum information of infalling matter is rapidly diffused across the entire interior while classical observables and coarse-grained geometry remain unaffected. Under the assumption that information has diffused throughout the interior, we consider the difficulty of the information-theoretic task that an observer must perform after crossing the event horizon of a Schwarzschild black hole in order to verify a violation of monogamy of entanglement. We find that the time required to complete a necessary subroutine of this task, namely the decoding of Bell pairs from the interior and the late radiation, takes longer than the maximum amount of time that an observer can spend inside the black hole before hitting the singularity. Therefore, an infalling observer cannot observe monogamy violation before encountering the singularity.Comment: 26 pages, 3 figures - v2: added references, small tweaks - v3: corrected typos to reflect final published versio

    Identifying ILI Cases from Chief Complaints: Comparing the Accuracy of Keyword and Support Vector Machine Methods

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    We compared the accuracy of two methods of identifying ILI cases from chief complaints. We found that a support vector machine method was more accurate than a keyword method

    Navigating later life transitions: An evaluation of emotional and psychological interventions

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    Transitions in later life, for instance retiring from paid work, changing career, ending or starting a relationship, can have a major impact on people’s lives and their wellbeing. Recognising a gap in preventative support for transitions such as these, the Calouste Gulbenkian Foundation (CGF; UK Branch) has funded a number of projects that provide group-based psychological and emotional support as part of its Transitions in Later Life (TiLL) programme. CGF and the Centre for Ageing Better partnered on the evaluation of two of these courses — Working Longer and Living Life to the Full, a two-day course run by Cheshire and Wirral Partnership NHS Foundation Trust (CWP) and Changing Gears, a three-day course run by Age & Opportunity in Dublin, Ireland. The aim of the evaluation was to find out what impact the courses had on individual attributes that would help people be better prepared for later life transitions; what changes people make as a result of the courses; and what practice, resources or processes in the organisations are important in ensuring their implementation and efficacy

    Branches of the Black Hole Wave Function Need Not Contain Firewalls

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    We discuss the branching structure of the quantum-gravitational wave function that describes the evaporation of a black hole. A global wave function which initially describes a classical Schwarzschild geometry is continually decohered into distinct semiclassical branches by the emission of Hawking radiation. The laws of quantum mechanics dictate that the wave function evolves unitarily, but this unitary evolution is only manifest when considering the global description of the wave function; it is not implemented by time evolution on a single semiclassical branch. Conversely, geometric notions like the position or smoothness of a horizon only make sense on the level of individual branches. We consider the implications of this picture for probes of black holes by classical observers in definite geometries, like those involved in the AMPS construction. We argue that individual branches can describe semiclassical geometries free of firewalls, even as the global wave function evolves unitarily. We show that the pointer states of infalling detectors that are robust under Hamiltonian evolution are distinct from, and incompatible with, those of exterior detectors stationary with respect to the black hole horizon, in the sense that the pointer bases are related to each other via nontrivial transformations that mix the system, apparatus, and environment. This result describes a Hilbert-space version of black hole complementarity.Comment: 25 pages, 2 figures; v2 added citations; v3 fixed a typo in sec 2.5 + 1 citation; v4 expanded discussion in sec 2, more citations; v5 small typo fixes to reflect published versio

    Adaptation without natural selection

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    Document is itself an extended abstract

    Comparative Analysis of ACAS-Xu and DAIDALUS Detect-and-Avoid Systems

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    The Detect and Avoid (DAA) capability of a recent version (Run 3) of the Airborne Collision Avoidance System-Xu (ACAS-Xu) is measured against that of the Detect and AvoID Alerting Logic for Unmanned Systems (DAIDALUS), a reference algorithm for the Phase 1 Minimum Operational Performance Standards (MOPS) for DAA. This comparative analysis of the two systems' alerting and horizontal guidance outcomes is conducted through the lens of the Detect and Avoid mission using flight data of scripted encounters from a recent flight test. Results indicate comparable timelines and outcomes between ACAS-Xu's Remain Well Clear alert and guidance and DAIDALUS's corrective alert and guidance, although ACAS-Xu's guidance appears to be more conservative. ACAS-Xu's Collision Avoidance alert and guidance occurs later than DAIDALUS's warning alert and guidance, and overlaps with DAIDALUS's timeline of maneuver to remain Well Clear. Interesting discrepancies between ACAS-Xu's directive guidance and DAIDALUS's "Regain Well Clear" guidance occur in some scenarios

    If you can't be with the one you love, love the one you're with: How individual habituation of agent interactions improves global utility

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    Simple distributed strategies that modify the behaviour of selfish individuals in a manner that enhances cooperation or global efficiency have proved difficult to identify. We consider a network of selfish agents who each optimise their individual utilities by coordinating (or anti-coordinating) with their neighbours, to maximise the pay-offs from randomly weighted pair-wise games. In general, agents will opt for the behaviour that is the best compromise (for them) of the many conflicting constraints created by their neighbours, but the attractors of the system as a whole will not maximise total utility. We then consider agents that act as 'creatures of habit' by increasing their preference to coordinate (anti-coordinate) with whichever neighbours they are coordinated (anti-coordinated) with at the present moment. These preferences change slowly while the system is repeatedly perturbed such that it settles to many different local attractors. We find that under these conditions, with each perturbation there is a progressively higher chance of the system settling to a configuration with high total utility. Eventually, only one attractor remains, and that attractor is very likely to maximise (or almost maximise) global utility. This counterintutitve result can be understood using theory from computational neuroscience; we show that this simple form of habituation is equivalent to Hebbian learning, and the improved optimisation of global utility that is observed results from wellknown generalisation capabilities of associative memory acting at the network scale. This causes the system of selfish agents, each acting individually but habitually, to collectively identify configurations that maximise total utility

    Battery Fault Detection with Saturating Transformers

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    A battery monitoring system utilizes a plurality of transformers interconnected with a battery having a plurality of battery cells. Windings of the transformers are driven with an excitation waveform whereupon signals are responsively detected, which indicate a health of the battery. In one embodiment, excitation windings and sense windings are separately provided for the plurality of transformers such that the excitation waveform is applied to the excitation windings and the signals are detected on the sense windings. In one embodiment, the number of sense windings and/or excitation windings is varied to permit location of underperforming battery cells utilizing a peak voltage detector

    The Barriers to Disclosure and Access to Specialist Services for Ex-Armed Services Personnel in the Criminal Justice System in Wales

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    Executive SummaryThis study was designed to evaluate the barriers to identification and access to specialist services for ex-armed services personnel (ex-ASP) within the criminal justice system (CJS) in Wales. This evaluation was commissioned by IOM Cymru SToMP and independently conducted by researchers at the University of Swansea.The research was conducted between August – December 2018 across police, probation and prison services throughout Wales, as well as with relevant third sector organisations. Primary research included quantitative, qualitative and observational methods and secondary quantitative data was also used. Data included every police force, every prison and a geographically spread number of probation services across Wales. In terms of formal qualitative data, a total of 58 individuals were interviewed across these sectors. This included both staff and service users. Many others were spoken to informally through visits to institutions and attendance at meetings.The data highlighted specific issues within each sector, as well as broader ranging barriers across the criminal justice system. Operational factors were the key barrier to identification, particularly across police and probation services where, in the majority of services, service users were not directly asked if they had ever served in the armed forces. Greater availability of information, for both staff and service users, was also highlighted as a key operational issue. This was particularly shown to be the case for service users who may choose not to identify themselves. Other potentially disadvantaged groups in terms of identification and accessing specialist services were women; individuals convicted of sexual offences; individuals serving short custodial sentences or on remand and those serving community orders. Access to services was largely location dependent, both in terms of the help available and the support offered to access it. There also appeared to be a disparity between the provision offered by the third sector in prison, when compared to the experiences of individuals who had tried to access this help once back in the community. Overall, there was a clear need for greater collaborative working between the CJS and third sector, as well as for a substantial improvement in data recording and monitoring across the board

    Consistency Conditions for an AdS/MERA Correspondence

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    The Multi-scale Entanglement Renormalization Ansatz (MERA) is a tensor network that provides an efficient way of variationally estimating the ground state of a critical quantum system. The network geometry resembles a discretization of spatial slices of an AdS spacetime and "geodesics" in the MERA reproduce the Ryu-Takayanagi formula for the entanglement entropy of a boundary region in terms of bulk properties. It has therefore been suggested that there could be an AdS/MERA correspondence, relating states in the Hilbert space of the boundary quantum system to ones defined on the bulk lattice. Here we investigate this proposal and derive necessary conditions for it to apply, using geometric features and entropy inequalities that we expect to hold in the bulk. We show that, perhaps unsurprisingly, the MERA lattice can only describe physics on length scales larger than the AdS radius. Further, using the covariant entropy bound in the bulk, we show that there are no conventional MERA parameters that completely reproduce bulk physics even on super-AdS scales. We suggest modifications or generalizations of this kind of tensor network that may be able to provide a more robust correspondence.Comment: 38 pages, 9 figure
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