5,450 research outputs found
Rescuing Complementarity With Little Drama
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
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
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
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
Comparative Analysis of ACAS-Xu and DAIDALUS Detect-and-Avoid Systems
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
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
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
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
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
- …